DMA reverts to PIO

Wed, 2007-07-11 08:30 by admin · Forum/category:

The stuttering DVD drive or the lame hard disk

Table of contents

for this article

Quick solution

This is the recommended solution. If you're not interested in the details, but just want to fix this problem as quickly as possible:

  1. Internet Explorer: click, Firefox and other browsers: right-click here.
  2. Internet Explorer: Despite any warnings click on the [Open] or [Execute] buttons as required to execute the file resetdma.vbs.

    Firefox and other browsers: Save the file resetdma.vbs to your hard disk. Double-click on the file in Windows Explorer and allow it to be executed.

    (If you fear that this web site could be malevolent, you could use the manual method instead, which is described below. You can also download, save, and inspect the program with an editor like the Windows Notepad. It is a script text file.)

  3. If the program found any ATA or SATA channel to reset, reboot your computer and test all drives.
  4. If the problem is still not solved, set the offending channel to PIO manually, reboot your computer, set the channel back to DMA, and reboot again.
  5. Please report your results here. Thanks!

Please note that this works only with the Windows drivers. If your device had its own manufacturer's drivers installed, this program cannot fix the problem and will not do anything to them. Instead it will report that no resettable DMA channels were found.

Note also that many CD and DVD drives only use UDMA-2, because their data rate is much lower than that of a hard disk. This is normal and no reason to worry.

If you are interested in the details, read on.

The program tries to reenable DMA in the registry exactly as described below, for all suitable (S)ATA channels. Windows then redetects the DMA status after the next reboot.

If you use the program again after a short while, it may again report that it has reset the channels. This is normal behavior and not a sign of any problem.

General description

This article also applies to Windows 2000. (Peter Frank reported successful application on Windows 2000 with Service Pack 4.)

DMA is an abbreviation for Direct Memory Access, an access method for external devices where the data transfer is not done by the central processor, but by a small special processor called DMA controller. It uses a procedure called cycle stealing, where the central processor memory access cycles are delayed for very short times to intersperse DMA controller memory access cycles. Some newer, faster DMA modes are called UDMA (Ultra DMA).

The alternative, slow and inefficient data transfer mode is called PIO, Programmed Input-Output, where the central processor transfers data byte for byte or word for word. This requires many processor commands for each data word and therefore causes a high and unwanted processor load.

A typical symptom of PIO mode is slow data transfer, accompanied by high processor load, leading, for example, to a choppy video display.

Possible causes for falling back to PIO mode

The most frequent use why a CD or DVD port falls back to PIO mode is a scratched or otherwise unreadable CD or DVD. For example, some newer DVDs, initially from Sony, carry a copy protection scheme that relies on defective sectors. If you try, without using special software, to copy such a DVD (which doesn't work), then this can already trigger the problem.

However, there are a few reasons why a computer may use PIO instead of DMA, particularly when it's the hard disk port that falls back, not a CD/DVD drive port. For example, David Duberman reported in 2005 that some Dell computers have DMA disabled in their BIOS by default for the second hard disk. So it is a good idea to check the BIOS settings first.

2007-05-13 – Jason Paquette confirmed that the BIOS setting in his Dell computer was wrong too and prevented DMA mode. Correcting the BIOS setting immediately enabled the DMA mode.

A not so rare hardware problem is a bad or too long IDE data cable. You need 80-way cables, not the older ones with only 40 wires. With poor cables the device may work, but Windows will probably step down to lower DMA speeds or even to PIO.

A further cause may be waking from standby mode, if one of the involved components does not perform this process correctly.

2007-02-20 – Stefan Welte wrote that on an Elitegroupsystems K7S5A computer all IDE hard disks ran in PIO mode, because automatic device recognition was disabled in the BIOS. (The computer booted from a SCSI disk.) Enabling device recognition solved the problem without any further measures.

2009-06-27 – markvm confirmed again that the BIOS in a Dell computer prevented DMA mode. Please see his comment below. In his case a hard disk was not recognized by the BIOS. After enabling and starting the automatic recognition, everything fell into place nicely, and DMA was automatically enabled by Windows.

2009-11-19 – flemur13013 mentioned again in this comment that setting the disk recognition to "Auto" in the BIOS settings solved his problem of a slow, CPU-gobbling secondary hard disk.

Occasionally a chip set or controller driver is buggy, so check with the manufacturer for updates.

2007-03-01 – Francois Eraud reports one such case in a Sony laptop, regarding an ALI M5229 chip set controller, solved with driver version 4.008.

2008-03-30 – Arran located the elusive drivers for this ALI M5229 controller chip. Please read his comment For those with the ALi M5229 IDE Controller in the comments on one of the next pages.

Other reasons can show up in the event log, so check this first and see if you can find repeated Atapi errors recorded. If so, you likely have a hardware defect. You can use the procedures described on this page, but your computer will probably fall back to PIO mode again and again, until you solve the underlying problem, which may be located inside the device, on the motherboard, or in the IDE data cable and its connectors.

A dramatic example was reported on 2006-12-29 by David Hähningen:

If you (half asleep in the dark and with considerable force) try to put the ATA plug on the hard disk the wrong way around, the gap called "KEYPIN" (pin 20 on the plug) pushes pin 21 of the hard disk socket and bends it aside. (This pin is responsible for DMA requests of the hard disk.)

As the disk can no longer reach the host with its requests, there is a communications problem, and Windows XP switches into PIO mode. A blessing in disguise: You can still save the data, though slower than usual. ;)

Few will succeed in repairing the disk. Just pulling the pin straight may not quite cut it, as the connection to the printed circuit board is probably broken.

2007-02-07 – Carl Kaufmann wrote that he looked for a solution for a computer with an Intel chip set and found the Intel(R) Application Accelerator. As instructed, he first installed the Intel Chip Set Installation Utility, which already solved the problem (as observed in Task Manager). He went on anyway to install the accelerator. After that there was no longer any DMA/PIO choice in the controller options, but everything now works right automatically.

2007-05-15 – John Schumacher confirms:

I thought I was having this problem, but that isn't the case. My BIOS listed Ultra DMA as being disabled on all my drives. I looked for the Advanced Settings tabs for the IDE channels in Device Manager, but the tabs were no longer there. I ran Nero InfoTool, which confusingly listed DMA on for primary and secondary masters, but off for primary and secondary slaves. After doing some more searching, I found out that the Intel Application Accelerator I recently installed is the culprit. Running Intel Application Accelerator confirmed that everything was OK.

The Intel Application Accelerator can also have a quite adverse effect when it is run on an unsuitable processor. If in doubt, uninstall it and retest. (See the comment, Intel Application Accelerator by dkneyle = Ausie Davo.)

The trap

Windows contains a trap in which quite a few computers seem to get caught sooner or later. The trap was described in a Web article whose link no longer works (and also in another one mentioned below):

The crucial paragraphs are:

PIO mode is enabled by default in the following situations:
For repeated DMA errors. Windows XP will turn off DMA mode for a device after encountering certain errors during data transfer operations. If more that six DMA transfer timeouts occur, Windows will turn off DMA and use only PIO mode on that device.

In this case, the user cannot turn on DMA for this device. The only option for the user who wants to enable DMA mode is to uninstall and reinstall the device.

Windows XP downgrades the Ultra DMA transfer mode after receiving more than six CRC errors. Whenever possible, the operating system will step down one UDMA mode at a time (from UDMA mode 4 to UDMA mode 3, and so on).

Of course, drive firmware being quite complex and certainly containing programming defects of its own, it is not all that difficult to produce such errors. In my case a scratched DVD and later also an unreadable (overburned) CD did the trick, got the drive to choke and Windows to disable DMA for good. Later my hard disk hiccupped just once and also went back to PIO for good.

I had been using my laptop for DVD viewing for years, until I inserted a borrowed and heavily scratched DVD. The player and apparently even the DVD drive choked on it, and when I finally got the DVD to play, I found that playing was jerky and processor load was 100%, roughly half of which was system overhead.

This indicated that the drive had reverted from the usual UDMA (Ultra Direct Memory Access) mode 2 to PIO (Programmed Input Output) mode. No amount of resetting or changing the relevant registry parameters from 1 (try DMA) to 2 (force DMA) helped. Stubbornly the drive kept using PIO mode, and Windows even changed these settings back to 0 (use PIO only).

The following text will refer to the secondary IDE port because that is more often affected, but essentially the same also holds for the primary IDE port, to which the main hard disk is connected in most computers.

Before you begin to work on the problem, log on as Administrator or as a user with administrator rights.

Check Your IDE Port Mode

First check what mode your secondary IDE port is currently working in. Go to Device Manager: right-click on My Computer, select Properties, click on the Hardware tag, click on the Device Manager button, click on the plus sign to the left of IDE ATA/ATAPI Controller, double-click on the secondary IDE channel, click on Extended Settings and check whether it is set to DMA when available. Directly underneath that setting is a grey field that shows the actual working mode of your IDE channel. You want the highest possible DMA or Ultra DMA mode there, and you definitely don't want PIO mode.

If the Extended Settings tab is not there, perhaps another driver is used, probably from the manufacturer of the IDE ATAPI controller. You can still perform a simple test. In the Task Manager activate the option View, Show kernel times. Then put a high load on the device, for example by copying a large file, and check whether the kernel times are minimal (red line). If you observe considerable kernel times, roughly around half of the total load, then the device is running in PIO mode, which is bad. The whole purpose of the DMA mode is to relieve the processor (in kernel mode) of this load.

Assuming the Microsoft IDE ATAPI driver, normally you don't have to use the registry editor, because the normal settings are also available through the properties dialog for the IDE port, but if you want to look at it anyway, the parameter for the secondary IDE port can be found through regedit.exe at


It is named Scsi only for historic reasons. Scsi Port 0 is the primary IDE port, to which presumably your hard disk is connected.

After trying various remedies—in vain—I found the abovementioned article and went to work again. I uninstalled the DVD drive in Device Manager and rebooted, but that did not help either.

So I searched for more and better information, then I went on and did the following.

Re-enable DMA using the Registry Editor

This chapter describes the manual way to do what the quick solution at the top of this page does automatically through a script program. If you're not interested in the details, you can back up to the chapter "Quick solution" above and run the script.

My thanks go to my fellow MVP Alexander Grigoriev who taught me this method.

Run REGEDIT. Go to the following key:


It has subkeys like 0000, 0001, 0002, etc. Normally 0001 is the primary IDE channel, 0002 the secondary, but other numbers can occur under certain circumstances. You have to go through these subkeys and check the DriverDesc value until you find the proper IDE channel.

Delete MasterIdDataChecksum or SlaveIdDataChecksum, depending on whether the device in question is attached as master or slave, but it can't actually hurt to delete both. Reboot. The drive DMA capabilities will be redetected.

Note that many CD and DVD drives only use UDMA-2, because their data rate is much lower than that of a hard disk. This is normal and no reason to worry.

2006-01-19 – Horst Schülke wrote that it is sufficient to empty the content of these values. But you can also delete the values entirely. Windows will automatically recreate them anyway, with new content.

Open Device Manager again and check whether the device is now actually using DMA mode. If so, congratulations, you've made it (at least until the next time Windows disables DMA). If not, you may have to change the IDE channel setting from PIO back to the highest available DMA mode and reboot again.

Many thanks to Tomáš Souček, Peter Götz, Alex Vaillant, and Cory Culbertson for piecing together the following information:

There are three keys that work together:


Each bit in these values means a transfer mode that the device may or may not be capable of. Somewhere at MS some of these bits can be looked up.


This is the actual mode the device is running at.


This entry may be the problem child. Peter wrote: "Normally not present in XP, it is created as a reaction to errors. This entry has absolute priority." However, there are doubts whether this is the absolute truth. It is still not entirely clear where this entry comes from. Erasing it or setting it to a DWORD value of 0xFFFFFFFF, rebooting, re-enabling DMA mode, and rebooting again seems to have solved the problem in some cases.


This entry contains the user's setting, manually entered in the advanced device properties. Has the same structure as MasterDeviceTimingMode. This entry appears when the user sets a limited mode manually, such as PIO only.

Another key that seems to create the problem is MasterIdDataChecksum.

All these parameters also exist for the slave drive as SlaveDeviceTimingMode, etc.

More information is needed. If you know anything, please click on Add new comment at the end of this article and write it down.

Alternative Method—Uninstalling the Port

1. Uninstall the secondary IDE port

Attention: Do this only if you use the Microsoft IDE driver that comes with Windows or if you have the driver on hand, because otherwise you may find yourself unable to reinstall the proper driver.

To uninstall the port along with its driver, open Device Manager as follows. Right-click on My Computer, select Properties, click on the Hardware tag, click on the Device Manager button, click on the plus sign to the left of IDE ATA/ATAPI Controller, right-click on Secondary IDE Channel, click on Uninstall. Deactivating is not enough.

Reboot to make the changes active and permanent.

After booting Windows will automatically reinstall the IDE channel and the DVD (or CD) drive. This Plug-n-Play process can take a little while, so give it a minute after the boot process finishes.

2. Check or reactivate DMA

But this may not always be not enough, because unfortunately Windows does not always automatically activate DMA on a DVD or CD drive. You have to check and, if necessary, tell Windows to try to use DMA first. It is possible that Windows XP with Service Pack 2 re-enables DMA automatically on reboot, but I have not tested this yet.

To re-enable DMA, go to Device Manager again. Right-click on My Computer, select Properties, click on the Hardware tag, click on the Device Manager button, click on the plus sign to the left of IDE ATA/ATAPI Controller, double-click on the secondary IDE channel, click on Extended Settings and change the relevant setting from PIO only to DMA when available.

On Windows NT and 2000 you now have to reboot a second time, but Windows XP applies the change instantly. Then you can go to the same place in Device Manager again and check whether the device is now actually using DMA mode. If so, all is well.

Note that many CD and DVD drives only use UDMA-2, because their data rate is much lower than that of a hard disk. This is normal and no reason to worry.

3. Driver is not intended for this platform

If you keep getting the following error message, please read on:

There is a problem installing this hardware.

IDE channel

An error occurred during the installation of the device. Driver is not intended for this platform.

2005-03-30 – Johannes B. wrote: The reason for this error is often that Daemon Tools or Alcohol 120% are installed. In this case the solution described below would not work. But when you uninstall these programs and then restart Windows, it will then install the device drivers without any further problems.

If these programs are not installed, then one possible way out is to rename C:\WINDOWS\system32\drivers\atapi.sys (or a similar path on your computer) to something like atapi.old.

If that's not possible, you can try it from the repair console (boot from the Windows install CD and select the repair console).

If Windows always automatically recreates atapi.sys, you can try renaming it in safe mode or from a command line window or you can try to rename or remove it in the driver cache as well.

Desensitize Your Computer's IDE or SATA Channels

There's a bit more to it. The following article offers a way to reduce the incidence of this problem, although it still doesn't solve it altogether.

IDE ATA and ATAPI Disks Use PIO Mode After Multiple Time-Out or CRC Errors Occur

Do read this article because it contains a useful long-term workaround. But you have to go through the procedure described here to re-enable DMA first.

Assuming you've done that, insert the ResetErrorCountersOnSuccess registry values mentioned in this article into both the primary and the secondary IDE port registry keys as described.

Unfortunately this is only a half solution, because when you enter an unreadable DVD, you will get 6 errors in a row, and the IDE channel will revert to PIO mode, but at least when you pull out the DVD in time and then insert a good one, the error counter will be reset and it will at least be a bit more difficult for Windows to hobble your IDE drive.

A little warning: One user reported that by mistakenly putting the value into the parent key, rather than into one of the 0000, 0001, 0002, etc., subkeys, he was accused by Microsoft's Genuine Advantage check of using a pirated copy of Windows and therefore denied online updates.


Useful info on re-enabling DMA. No more jerky video from primary slave! Thank you

Thank you for a very helpful article. After applying your fix I saw a 10x speed improvement!

Don't mention it!!! After months of trouble-free operation, DVD playback suddenly started to crap out on me, and your site was the only one I could find that remedied this problem. I had been trying to fix it for several weeks when I found it, and boy was I happy. I'm the one who needs to thank *you*!!! Thank you!!! :)

Thank you for the great page on DMA/PIO issues. I had a problem caused by Daemon tools that you covered on your page. Without your work I might never have solved this problem. I intend on donating again after my next paycheck.

You ROCK! Your write-up on Windows setting DMA back to PIO saved me. I was about to take a 12 gauge to my computer. My DVD player wouldn't work for SHIT (stuttering, dropping frames, etc.). I uninstalled my secondary IDE controller, re-booted, & problem solved. THANKS!

Your DMA reverts to PIO page relieved me from horrible sound stututustuttuttering. [...] Hard disk went from PIO mode back to Ultra DMA mode 5 when I uninstalled primary IDE channel in device manager and XP reinstalled it. Thanks.

I love you...
no i don't—but I'm really greatfull that you published this site [...] as I was quite desperate and 24 hours mentally down because my harddisk only managed 2,2 MB/sec (now, thanks to you: 66,2)
best wishes!

Wonderful Dude,
I just want you to know that your posts on how to fix choppy DVD players saved my butt tonight. I love the fact that I can go and search for an answer on the internet, and a good soul such as yourself will have taken the time to post such a clear and excellent series of solutions. [...]

I just wanted to thank you for the information [on this page]. After noticing that my laptop's CD/DVD drive started exhibiting the dreaded "choppy playback" from nowhere (probably caused by trying to read a poorly burned homework assignment handed out by one of my professors a dozen times) I found your advice after a quick search on how to correct the problem. After a few minutes of reading, using the provided script, and rebooting, my drive successfully reverted back to DMA mode from PIO.
Just wanted to give my thanks and have myself counted among the satisfied visitors who were able to fix the issue without any problems. I especially appreciated the down-to-earth explanations for and solution to the playback choppiness. CDs/DVDs play like a dream again, and that really makes my day.

I also wanted to thank you. I almost despaired. For no discernible reason all movies from my DVD drive became jerky. Cleaning the registry and scanning for viruses were also unsuccessful. I was already resigned to the thought of returning the laptop to the manufacturer, because I thought the drive was broken. Luckily there is the Internet and dedicated people like you, who help with good tips.
Many thanks for your work; the article is truly excellent. You're my savior, unthinkable now that I had almost reinstalled the computer.
I hope that many, who have the same problem, find your article.

Thank you very much for your online help to my DMA problem (DMA reverts to PIO). I had been banging my head against the wall for a few weeks before I found your site. The .vbs program worked perfectly to fix my infuriating iTunes & audio distortion problems. For this, I have donated $10 to your site.

Comments, discussion

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Typical symptom: PIO mode (see comment 761). JPG image30.33 KB

Once you have an account,

Fri, 2008-01-04 16:41 by admin

you might as well come back. How about the lighter side? (:-)

Glad the problem could be solved.

Thank you so much!

Fri, 2007-12-14 02:39 by rvn (not verified)

Quick solution of DMA=>PIO problem saved an urgent project. Man, I owe you money :-)

Oh, I found Donations at the top right corner ))

Ah, donations!

Fri, 2007-12-14 09:07 by admin

Yes, I can always do with a little bit of support here. The web site eats up time and eats into the time for other projects.

Anyway, glad the page solved your problem. It is still one of the most stunning Windows phenomena. I don't dare to put a price tag on the damage that software designer has done with a single stroke of genius. Anyone care to do an estimate? It begins with the likelihood that any computer at any time gets a badly scratched DVD to read.


Mon, 2007-12-10 17:37 by gapper100 (not verified)

Woah, thank you SO much! I tried lots of things to put my Harddisks back in UDMA-Mode 6, but none of them worked; until this one!

You're welcome

Mon, 2007-12-10 18:21 by admin

Glad it worked again. It's such a widespread problem ...

DMA resets to PIO

Sun, 2007-11-25 12:09 by Ozana (not verified)

Windows XP SP2, DVD-RW drive LG still revert to PIO mode. Slow reading and riping (1x) DVD video, buffer up to 100%, CPU up to 99%

My solution:
edit registry ResetErrorCountersOnSuccess=1 by KB817472:
IDE ATA and ATAPI disks use PIO mode after multiple time-out or CRC errors occur

and install hotfix KB920918:
An IDE device runs in PIO mode instead of in DMA mode after you update the firmware for the device in Windows XP
download at

AAARGH !!!!!

Sun, 2007-11-25 20:27 by politik (not verified)

I update the firmware on my drives regularly so I gave this a try and STILL PIO mode !!!!! Trying a bootable CD with Hutil, a Samsung drive utility program that supposedly manually sets the DMA for Samsung drives but I'm getting partition errors....uuuuughhhh.

"Do no touch the trim"

Interesting hotfix, thanks!

Sun, 2007-11-25 13:44 by admin

The hotfix is documented only as a cure for a problem after an IDE/ATAPI device firmware change. Had you changed the firmware or does this hotfix also help (in an undocumented way) when the firmware has not been changed? That would be interesting.

By the way, the hotfixes (different language versions) can be found through the search function. They are here:

Still stuck in PIO mode

Sat, 2007-11-24 17:27 by politik (not verified)

First let me thank you for this site AND this topic. Was aware of DMA/PIO mode but I had no idea how critical that setting is. I also thought those "Ultra DMA" cables were a rip off but switching from an 80 pin standard cable to an Ultra DMA cable increased my boot drive from DMA 2 to DMA 5.

Previously my read and write maxed at 1.2 to 1.4x but I was ripping and burning images to/from the culprit drive. Using my boot drive that works in DMA 5, reads are maxing out at about 4x and writes max out at about 9x so umm yea....BIG UPS !!!!!!

Here's my set up:

Windows XP Home Edition SP2

Primary master: Seagate ST34001MA 40G drive
primary slave: Samsung SP2514N 250G drive (stuck in PIO mode)

primary controller uses Ultra DMA cable

Secondary master: TSSCorp CDDVDW SH-S202G
secondary slave: TSSCOrp CDDVD/W TS-H552B

also under controllers is:

Intel(R) 82801EB Ultra ATA Storage Controllers

Still can't get the Samsung hard drive to get into DMA mode. I've verified that this drive does work in DMA mode. I've tried unintalling/reinstalling all controllers and devices. I tried the vbs script, doing the suggested registry changes manually, but this drive just seems to wanna cruise in PIO mode. I physcially removed the culprit drive from the PC, BIOS and Windows recognized that the drive was gone, burned a few images and everything flew at DMA speeds, rebooted a bazillion times and when I put the culprit drive back in, it's still in PIO mode.

My next step is to check the Event Viewer for any clues. Tried finding some kind of utility for the Intel 82801EB controller or any other info but nothing yet. I REALLY wanna keep all these huge files off the boot drive and copying the images from the culprit drive to the super fast boot drive takes so long that it negates all the speed increases I've gained. Any suggesitons ? Thanks !!!!!

looks like it's at drive level

Mon, 2007-11-26 00:25 by politik (not verified)

Finally got Hutil to boot off CD. diagnostic test for DMA Read failed but just for grins I found the option to manually set the DMA speed. Tried all different values 33 up to 133 and none worked. There still may be something in Windows that is "stuck" in PIO mode, but there definitely seems to be an underlying hardware problem. I'll take this up with Samsung and Intel for now. I'll be back for results if anyone is as curious as I am to get to the bottom of this.

Oh yeah....some results from the diag:
"DMA Mode: Support"
"Multiword DMA Mode 2 and below supported"
"Multiword DMA Mode 2 is not sleected"

There didn't seem to be a "Use DMA" or "DMA on" option for the entire drive, but the diag tool did report that the drive was running at DMA speeds. Is "Multiword" DMA something different from regular DMA ? Do I need to somehow select "Multiword DMA Mode 2" ?

"Do no touch the trim"

Samsung disk drives

Mon, 2007-11-26 07:06 by admin

I've read Samsung before in this context. Certain new Samsung hard drives seem to be incompatible with certain IDE/ATAPI controllers. For fun, press Ctrl + F now, enter Samsung, and search this page. You'll get a whole bunch of hits.

I count myself lucky, because I write this on my computer, which runs on a Samsung 500 GB hard disk, and I have no problems.


Tue, 2007-11-27 01:42 by politik (not verified)

Yeah just searched the page and in the email section, someone says they had the same problem with the same model Samsung drive and ended up having to switch to another manufacturer. A new acronym "RTFSP" Read the _ _ _ _ _ _ _ small print" Thanks for the site though. Stil learned a lot.

"Do no touch the trim"

The drive or the controller?

Tue, 2007-11-27 06:31 by admin

Now it would be interesting to know whether it's just some, not all Samsung drives that are broken or whether it is indeed an incompatibility between Samsung hard drives and certain controllers. The next question is, which controllers? What motherboard do you have? Which controller chip?


Sat, 2007-11-24 18:39 by admin

Try a BIOS update first. Occasionally that can help.

Some drives are incompatible with some controllers. You seem to have the bad luck to have such a case, assuming that there is no other hardware problem.

If that is so, you have only two choices. Either you swap the motherboard or you swap the drive. Sorry to be the bringer of bad news.

dma reverting to pio..

Wed, 2007-11-21 09:07 by sorinelkat (not verified)

i took the classical manual approach...
went to


and deleted the 2 keys for my primary IDE channel..
"MasterIdDataCheckSum".. and "SlaveIdDataCheckSum"..
Rebooted and...
Magic! You saved me a couple of precious hours needed to move the data from the windows partition and reinstall Windows...

Thank you.

"I'd rather be hurt by the Truth than rejoyce in the comfort of lies..."

Alternative Method Safe on Boot Drive?

Sun, 2007-11-11 14:14 by golddave (not verified)

I am having problems where the boot times on my desktop PC are incredibly slow (it could take 10 to 15 minutes). The quick solution tool does not work for me since my PC doesn't use the Windows drivers. I used the alternate method to fix my CDROM drive a while back but am a little hesitant to use this method on my main primary booting drive. I'm worried about making things worse. Is it safe to use on the drive I boot from?

Difficult to say

Sun, 2007-11-11 14:48 by admin

The first question is whether the system can boot from the drive also through the Windows/Microsoft driver. If it can, then the method is fairly safe.

If not, then you would have to make sure you make no mistake and always have the proper driver installed and working. It can be done, but you have to be careful. Even if it fails, there are methods to install a third-party driver. One of these methods is to do a repair installation of Windows (see the general instructions) and supply the third-party driver during the repair installation process.

Most standard controllers can boot with the Windows/Microsoft driver. The typical exception would be a third-party RAID controller.

If you can remember how Windows was first installed on the computer, then you may also remember whether you had to supply a special disk driver early in the installation process. If so, then the system probably wouldn't boot throught the Microsoft driver. If, however, you could install Windows normally, then install the third-party driver later, then Windows could obviously boot through the Microsoft driver and you don't have to worry now.

This is a Dell machine so I

Sun, 2007-11-11 16:54 by golddave (not verified)

This is a Dell machine so I didn't do the install. I have no iudea what driver they are using besides that it is not the MS one.

Dell's customer support?

Sun, 2007-11-11 21:54 by admin

I hear that Dell has a reasonable customer support. Have you called them already? They may also have the driver for download.

There is also still the question whether the cause of the problem is, in fact, PIO mode or whether it is something else.

DMA Stuck in PIO

Mon, 2007-10-22 15:55 by Rabotnik

I seem to have the same problem as one of the earlier e-mailed comments. Issue is with ASUS A7A266 motherboard and large hard drive.

Two years back, I tried to add a Samsung Spinpoint 160GB drive as a slave on Primary IDE, with 120GB IBM as master. This defaulted to PIO mode, nothing seemed to persuade it to UDMA5, so I gave up, and stuck it in an external Icybox enclosure, where it works great.

Recently the 120GB IBM decided to fail, so I bought a 320GB Seagate ST3320620A. Installed XP, then SP2 when I noticed the install slowing down. Checked, and yes, stuck in PIO. Tried a few tips uninstalling Master IDE Controller, tweaking registry, earlier version of (reportedly buggy in SP2) Atapi.sys, but nothing works. As soon as any of the MasterDeviceTimingMode or related keys are deleted, on re-boot the CRC errors are detected by Atapi.sys and logged as 6 errors in Event Viewer, a Controller Error on /Device/Ide/IdePort0 is logged and I guess this is when XP restricts Device 0 to PIO. I have an older 80GB WD drive and it picks up UDMA5 without trouble (but it is sooooo noisy compared to the Seagate - HDD designs have progressed amazingly). I also have BIOS 1011, and this release supports 48 bit LBA. There's a Beta 1013 BIOS update which I admit I haven't tried - anyone brave enough to try a Beta version 13 ?

I also replaced the IDE cable as the old one was a bit gnarled, but no difference.

I would conclude this is a firmware conflict between the ASUS A7A266 / BIOS and hard disks requiring 48 bit LBA. I am pondering the IDE controller card solution, but not sure if I want to spend any more money on this 6 year old system, so I'll probably have to live with the 80GB WD. I foresee the 320GB Seagate in the Icybox attached to a brand new system (like the look of HP M8180) before Christmas.

Any more ASUS A7A266 owners out there with the same problems?

I know your problem... I've

Thu, 2007-11-08 09:40 by Whimpy (not verified)

I know your problem...
I've had the same problem.

It's not a BIOS issue, it's a driver issue... is where I found an answer.

Interesting - thanks!

Thu, 2007-11-08 10:17 by admin

Rabotnik, if you read and apply this, please report back whether you could solve your problem.


Asus A7A266 and Large HDD

Wed, 2008-01-16 21:32 by Rabotnik

Ref comment from Whimpy 2007-11-08 and Hans-Georg, the link gave a solution. So it was definitely an ALi driver issue on the A7A266 board in my case. All I did was apply the IDE4008.exe update, carefully following the Readme instructions. No issues so far with my new SCSI 100 drives !!!!

Sorry for not coming back to this topic sooner. I actually stumbled upon the above link myself, so I thought I would post my success back here. The moral of this story - keep the faith and visit regularly where you made a post. Thanks to all.

Of course in the meantime, I splashed out on the new system. Well, I needed an excuse .............

Thanks a lot for the confirmation!

Thu, 2008-01-17 09:34 by admin

Good to hear about your experience. Confirmed cases with perfect solutions are most welcome.

[Have moved your comment into the thread.]

Time for a new motherboard

Mon, 2007-10-22 19:04 by admin

Computers stay usable a bit longer now than 10 years ago, but 6 years is still a stretch.

I believe your analysis is correct. I'd give the latest beta BIOS a test, but if that doesn't work, I think you'll be better off getting a new motherboard, probably a new case as well, so essentially a new computer, except that you don't need new hard disk and DVD drives. Most modern motherboards have both SATA and IDE/ATAPI connectors, so you can use all your existing hard disks on them. But you'd be open for the new ones.

SATA 2 is nothing to sneer at. I just stuck a new, silent Samsung 500 GB hard disk into my computer, and it's a joy to work with. The whole box is very nearly inaudible. And that's an already 2-year-old Asus A8N-SLI Premium motherboard (fanless heat pipe chip set design, only two big and quiet fans in the whole computer).


Latest ASUS A7A-266 BIOS - Unlucky 1013

Tue, 2007-10-23 20:58 by Rabotnik

Well, bit the bullet and flashed BIOS to 1013 Beta. Made no difference whatsoever. Deleted the MasterDeviceTimingMode and related registry keys, re-booted and as expected, the 6 Atapi.sys errors appeared in Event Viewer. Final conclusion - motherboard and its last-released BIOS incapable of communicating with >137GB hard drives in UDMA modes. Secondary conclusion - shopping for a new system.

Sorry for you

Tue, 2007-10-23 21:31 by admin

Sounds like bad luck. Well, good luck with the next, brand-new system. If it serves you well for another 6 years, that's not too bad, really.


p.s. Please click on reply when you want to reply.

Big, big THANK YOU

Tue, 2007-10-09 12:36 by GammyKnee (not verified)

My drive (LiteOn) was actually still listed as using UDMA in Device Manager, but it was behaving just like a PIO device (1x speed, maxing out one core of c2d). Your little vb script restored it to full speed. Thank you so much!

You're welcome

Tue, 2007-10-09 14:36 by admin

Glad it worked.

If you haven't done it already and if you find the time, please report your results here.


My fingers are crossed

Wed, 2007-09-26 20:58 by memacmur (not verified)

No idea why this suddenly started happening after years of good behaviour. But lately my DVD and CD drive keep getting punted down to PIO only mode.

I had found another reference with the instructions to uninstall, reinstall the IDE Controller, and have done that (multiple times), but it seems random as to how the drives come back. I am hoping that your hints to investigate the BIOS and Master/Slave settings may allow may to get back AND stay in DMA mode!


no success...

Tue, 2007-09-25 09:00 by aleksio (not verified)

Ok, I've now officially tried every single solution, except changing cables etc, as I believe that's not my problem since the computer has worked fine for a year.
But, when trying to delete the "MasterIdDataChecksum" in all my folders, it keeps comming back in two of the folders if I either reboot or try to configure the IDE channel in one or another way. I tried giving the MasterIdDataChecksum a value of 0xFFFFFFFF, this seemed to work slightly better, as when I rebooted the ide channel with the problem intially showed udma mode, but when i tested the hdd, it went back to PIO mode at once, and the MasterIdDataChecksum went back to it's "normal" value.

So, the only hope I'm holding on to now is that the problem might be solved if I can manage to do something with the two MasterIdDataChecksum's permanently.
Any tips of how that might be done?

Hardware errors

Tue, 2007-09-25 10:22 by admin

If you set the channel to DMA successfully, but it keeps falling back to PIO as soon as the device is working, that's a strong indication that there are many hardware errors on the data channel.

To find out what exactly causes these data errors, you can only swap things around. Try a different data cable. (Make sure you're using the right one anyway. A 40-wire cable may not work when you need one with 80 strands.)

Ultimately swap the hard disk. Connect it to another computer and check whether it has problems there too.

And read the comment, "Other causes" below. I keep seing computers with wrong master-slave jumper settings and unfavorable device arrangements in relation to the available IDE ports.


For some reason didn't solve the problem! :'(

Mon, 2007-09-24 06:33 by FatManMGS2 (not verified)


I hope I am not going to off track here!

I noticed someone had referrenced to your site off of the DELL support site for a problem where DVD playback was just awful; it "stutters" as you put it. The same is for me, in addition to it having difficulty installing from CDs (as well as completely failing...)

Anyway, the PIO settings *were* in place, and I rememebr burning an old, scratchy, scratchy Genesis CD right before this problem happening, and it made PERFECT sense for the cause, especially because the PIO was set instead of DMA. So, I changed it.

Changes worked...

Problems still there unfortunately :-(

All I did was download the registry editor and run it, to which it said it was successful, rebooted, and noticed the IDE was in fact changed, but the CD player still won't work (won't recognize CDs and won't install a game). Could this be a different issue? Could it be set to PIO somewhere else?

Thanks for the article anyway! Very well written!


Other causes

Mon, 2007-09-24 12:56 by admin

Hi FatMan,

the problem can have other causes. For example, if the DVD drive produces errors, it will fall back to PIO again, sometimes very quickly.

If it is still set to DMA, the next thing I would test is IDE port arrangement. It is best if the DVD drive is master on the secondary IDE port, while the boot hard disk is master on the primary IDE port.

So what's a master? The normal way to connect a master is:

  1. Set the jumper to master, not slave and not cable select.
  2. Connect the master drive to the end of the IDE data cable.
  3. Make sure that any second drive connected to the same IDE port has its jumper set to slave.

If that doesn't solve the problem, remove other slave drives. IDE is a bit quirky. A bad contact in a cable can cause nasty problems, for example. Swap the data cables between primary and secondary IDE port for a test.

Yet another possibility is that the drive itself is defective or incompatible. The easiest way to find out is to borrow another one and test that.

And there are always some more things that could cause the problems, like an incompatible driver, a defective motherboard, or a damaged Windows installation.

One of the few ways to find out is to swap every component. For example, you could lend your DVD drive to a friend and let him test it in his computer. If it shows the same problem there, dump it.

Good luck---Hans-Georg


Tue, 2008-04-22 10:42 by KindredSoul79

"So what's a master? The normal way to connect a master is:

1. Set the jumper to master, not slave and not cable select.
2. Connect the master drive to the end of the IDE data cable.
3. Make sure that any second drive connected to the same IDE port has its jumper set to slave."

I read, and followed your whole page on how to fix this problem. I ran the script 5 times. And still the secondary drive said device 0 was UDMA 2, and device 1 was PIO. Without reading this comment I thought "Maybe I can trick it into thinking it is UDMA. So I switched my DVD drive and CD drive around, and made DVD master, CD slave. BAM fixed the problem. Then I come here to post how my problem was fixed so other people could be helped, and I find you already suggested it. Classic

Confusion :-P

Mon, 2007-09-24 21:30 by FatManMGS2 (not verified)

The thing that makes this even worse is that I'm on a laptop; I don't think I can pop the DVD drive out without having to unscrew the entire thing :-/

I did find out that you're article in fact did work, and you're right: it does switch back right as I put the disk in.

Oh well, I can probably by an external DVD drive :-)

Thanks for the help!


Swap it

Mon, 2007-09-24 21:59 by admin

Laptop DVD drives aren't so difficult to take out, usually. Just a few screws, and the thing slides out.

You could visit a computer shop and ask them to put in another one for a test. Ask them beforehand whether they take the new one back if it doesn't work either.

Good luck again---Hans-Georg

Thanks a million!!!

Sun, 2007-09-09 07:35 by fcuk (not verified)

I've been banging my head on this problem for two months now and thanks to your article and solution, my laptop has reduce its booting time from 6 minutes down to 40 seconds! It has also stop locking up in really inconvenient times, like presentations and demonstrations! Really appreciate your help on this. Can't thank you enough. Fred

sound not continuous dvd drive

Sun, 2007-08-19 18:11 by georgianeagle (not verified)

thanks a lot guys this seems to work

PIO on primary channel (system disk)

Wed, 2007-08-15 11:38 by jvdgoor (not verified)

Thank you for your information. It helped to solve my problem. After a system crash windows was very slow in starting programs and opening files that were located on my primary disk (system disk). I had almost decided to buy a new harddisk when I read your article. I used the VBA script, rebooted, and the problem was solved. I am very happy, obviously.


Sat, 2010-02-27 17:42 by ian-in-northampton

Having read this part of the site from front to back and back again, I thought I'd found what I was looking for. Having tried everything I could think of to get my DVD and DVDRW drives working properly again - they worked fine, then they started playing audio and DVD with a stutter - up to and including a complete reinstall, I thought I'd found the solution.

Don't get me wrong: I'm thrilled for those for whom this worked. However, I tried the .vbs script - twice - but neither time did it have any effect. Then I tried the registry hacks (including the 'problem child' hack) - but again, no joy. My disappointment was very deep... :-( The channel in question remains resolutely stuck in PIO mode.

What is strange to me is that even the XP (SP2) reinstall (on a formatted hard drive) didn't work. Given the (very lucid) explanations of what's going on, I'd have thought a fresh install would reset everything - unless, somehow, XP interrogates a drive's firmware for some kind of error table?

What is strange, and I'd appreciate anyone's comment on this, is that for some reason, even after the fresh install, I have three primary IDE channels, three secondary IDE channels and three standard dual channel PCI IDE controllers. They line up like this:

Primary IDE Channel 1

Device 0

Device Type: Auto Detection
Transfer Mode: DMA if available
Current Transfer Mode: Not applicable

Device 1

Device Type: Auto Detection
Transfer Mode: DMA if available
Current Transfer Mode: Not applicable

Primary IDE Channel 2

Device 0

Device Type: Auto Detection (greyed out)
Transfer Mode: DMA if available
Current Transfer Mode: Ultra DMA Mode 5

Device 1

Device Type: Auto Detection
Transfer Mode: DMA if available
Current Transfer Mode: Not applicable

Primary IDE Channel 3

Device 0

Device Type: Auto Detection
Transfer Mode: DMA if available
Current Transfer Mode: Not applicable

Device 1

Device Type: Auto Detection
Transfer Mode: DMA if available
Current Transfer Mode: Not applicable

Secondary IDE Channel 1

Device 0

Device Type: Auto Detection
Transfer Mode: DMA if available
Current Transfer Mode: Not applicable

Device 1

Device Type: Auto Detection
Transfer Mode: DMA if available
Current Transfer Mode: Not applicable

Secondary IDE Channel 2

Device 0

Device Type: Auto Detection (greyed out)
Transfer Mode: DMA if available
Current Transfer Mode: Ultra DMA Mode 5

Device 1

Device Type: Auto Detection
Transfer Mode: DMA if available
Current Transfer Mode: Not applicable

Secondary IDE Channel 3

Device 0

Device Type: Auto Detection (greyed out)
Transfer Mode: DMA if available
Current Transfer Mode: PIO Mode

Device 1

Device Type: Auto Detection (greyed out)
Transfer Mode: DMA if available
Current Transfer Mode: PIO Mode

Can anyone see anything weird about that configuration - and what I might be able to do?

Note, by the way, that I've checked the BIOS for any possible settings to change - but nothing...

Unfortunately, now I can see no other way forward than to replace both optical drives - I'm assuming that one or both of them is bad. (Although both recognise and play data CDs and install programs no problem).

Is there any alternative - anything else I can try? I'd really value some input/help. TIA. Ian

what the real symptons are?

Mon, 2010-03-01 13:44 by lsattle

Question I have in reading your post is whether these drives are ever DMA after some repair attempts and then they revert back to pio.
That is, you did a reinstall. Did they first show as dma then revert to pio when used, or did they say pio from the start.

I have a small amount of experience in this area, but I've got to ask, what happens when you just have a master drive on the cable with no slave?
I am the guy that had the dell posting
Cable order was important for some unknown reason. The hard drive was dma when it was the master and pio when it was the slave.

IDE ports sometimes unreliable

Mon, 2010-03-01 17:05 by admin

Unfortunately I have already seen too many cases where things like this happen, like controllers not recognizing devices or not recognizing the proper DMA mode.

You have to check the master-slave jumper first, but if that is OK and the cable is OK, then you sometimes have to take it that the controller is not quite compatible with the hard disk or with the real world.

It may be a good idea to buy quality equipment from reputable manufacturers, rather than the cheapest motherboard available.

Both devices on one channel

Sat, 2010-02-27 22:05 by admin

If both devices on one channel always fall back to PIO, then the most likely explanation is that their shared cable is bad or the IDE port/controller on the motherboard.

Swapping the cable for a known good one would be a first test.

Intel Application Accelerator

Wed, 2007-08-08 02:12 by dkneyle (not verified)

I couldn't get my drives to operate in other than PIO mode, despite following all the instructions given here. I noticed a reference to Intel Application Accelerator. (After much damage with crashed PC) I uninstalled Intel Application Accelerator. BINGO. DMA now worked for Primary Master drive and DVD Master on Secondary. Reading Intel site, Application Accelerator is only intended for Pentium processors. I run a Celeron. So, if like me your machine is running like a dog, check whether you really should have application accelerator installed or not.

Ausie Davo

Bad hard drive?

Tue, 2010-01-05 20:28 by keith_leitch

This script has made a huge difference. I was achieving only speeds of 10MB/s or worse, but running the script boosted performance to as much as 92MB/s. However, it has raised a concern about my hardware.

When I ran the script once, the response message indicated that all four channels had been reset to UDMA. I ran it a second time, and the response message indicated that there were no channels available to reset. I interpreted this to mean that all the channels were in UDMA and that all was OK.

However, when I ran it again 5 minutes later, all 4 channels reset again. This seems to be the case over and over; after a few minutes, the script reports that it has reset the channels.

Is this normal, or does this mean that I have a hard drive causing channels to reset to PIO? If I do have a bad drive, how do I determine which one is causing the problem?

No problem, that is normal.

Tue, 2010-01-05 23:41 by admin

The program checks whether there is a registry key with drive error information and deletes that key.

After the drive is used for a short time, the key is automatically recreated. That is why the program reports it again, but this is normal.

You would have a problem only if a drive kept falling back to PIO mode.

works like a

Wed, 2010-02-24 21:07 by MR.Walker (not verified)

works like a charm
simply run & restart windows

Solved my problem

Mon, 2011-09-12 23:17 by marcolopes

Amazing info.
My XP was sluggish for the last few days. It was the Primary IDE channel working in PIO mode. VB Script solved everything!

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