DVD drives revert to PIO mode
 

They should ordinarily be Ultra DMA but they revert to PIO. The results? Massive CPU usage while playing a CD/DVD, especially when burning DVDs. If I burn a DVD while the drive is in PIO mode, the result is the buffer level being incredibly jumpy and my whole computer being so unbearably slow that I have to leave and come back when the burn is complete.

I don't know what causes it. Supposedly after X many failed reads, Windows turns back to PIO mode. There seems to be no way to stop this - besides not playing any media that might cause read errors, I guess. There are several methods to work around this, like setting the drive to reset the error count after one successful read. This worked for me once, it's not working anymore.

I've uninstalled the Secondary IDE Controller from Control Panel, uninstalled the drives, etc, and rebooted. Doesn't work. I've checked BIOS settings as well, which wasn't helpful.

But I need to be able to burn DVDs. Does anyone know anything else I can do? There needs to be some way to force Ultra DMA, but I can't find anything through Google.

What type of drive is this? Brand? Model number?
Have you checked the cables on the drive?
What operating system are you using?
Where do you count the 'failed reads'
Have you tried the drive using a disc-bootable linux distri like Knoppix?
Do you have the possibility to modify PIO/DMA settings in the BIOS (some BIOS don't let you specify the transfer mode)?
What kind of mainboard do you have?
Have you installed the lastest chipset drivers for your northbridge/southbridge/etc. ?
Is the system overclocked/do you have a heat problem?
Is the system working normally apart from the transfer mode issue?

cya
liquid

Looks like you tried most of the remedies already prescribed on the net, Eleo. How about if you uninstall the IDE port, and temporarily use an entirely different brand of DVD drive?

Ah yes, this is the most annoying 'feature' in Windows XP.

Use this link for directions on how to reset to DMA mode and force windows to use DMA:

http://neodon.blogspot.com/2006/07/l...ard-drive.html

Note that even though the link has you force DMA mode 6, Windows will automatically set the DMA mode to the maximum the drive supports up to mode 6. Also note this doesn't completely prevent windows from reverting back to PIO mode, but Windows won't set the device to PIO unless it see 6 consecutive errors rather than 6 cumulative errors which is the default.

Be sure to reboot after making the changes so Windows can autodetect the DMA transfer mode for each device.