CD-ROM and DVD-ROM drives can revert to using PIO mode, despite being set to use "DMA if Available." Here's how to make Windows XP redetect the DMA capabilities of the drives.
This behaviour occurs with the following conditions:
- Windows XP is the operating system
- A CD-ROM or DVD-ROM drive, which is known to support DMA mode now works only in PIO mode.
- The drive controller is set to use "DMA if available" but reports to be only in PIO mode.
Following is the mechanism that has worked for me, please try it at your own risk, it involves hacking the registry:
- Open RegEdit
- Find the following KEY:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ Class\{4D36E96A-E325-11CE-BFC1-08002BE10318}\000x
- The last four digits will be 0000, 0001, 0002, 0003, and so on.
- Under each key, delete all occurences of the following values:
MasterIdDataChecksum
SlaveIdDataChecksum
- Reboot the computer. Windows will now redetect DMA settings.
Source:
http://sniptools.com