here is something I wrote up about DMA back in 2002 that might help it tells you how to change it in the registry. I checked and the same registry key still controls the DMA so this should work.
Had not made a cd in months and when I did at high speed got errors and a defag seem to fix that problem next time I will test and record instead of record only.
I did also check my DMA settings and found that my main hardrive DMA settings were set to PIO only and Had to follow the procedure below to correct. I hate that xp will change these settings without any help from you.
To enable DMA mode using the Device Manager:
start then control panel then system hardware to
Open Device Manager.
Double-click IDE ATA/ATAPI Controllers to display the list of controllers and channels.
Right-click the icon for the channel to which the device is connected, select Properties, and then click the Advanced Settings tab.
In the Current Transfer Mode drop-down box, select "DMA if Available" if the current setting is "PIO Only".
If the drop-down box already shows "DMA if Available" but the current transfer mode is "PIO Only", then the user must toggle the settings.
Change the selection from "DMA if available" to "PIO only", and click OK. Then repeat the steps above to change the selection to "DMA if Available".
I found this did not work on one of my hardrives and had to use the following steps. I found that the hardrive did not have the 0xffffffff. When you right click and modify to change it to the above you only input the ffffffff not the 0x. I changed it then I could change from PIO Only.
The Default Value should be "IDE ATA/ATAPI controllers"
Go to "0001" key if your device is on Primary IDE Chanel or "0002" if your device is on Secondary IDE channel
and change the MasterDeviceTimingModeAllowed or SlaveDeviceTimingModeAllowed to 0xffffffff depending if your device is master or slave
close registry editor.
Go to device manager select "IDE ATA/ATAPI controllers" and the corresponding IDE chanel go to "Advanced Settings" Tab and Set Transfer Mode to PIO and then to DMA if available again