There can be many reasons why DMA option is not available.

If you go to your device manager, hard disk controllers, and see Primary & Secondary UDMA or UATA hard disk controller, you may not have this option available. You will need to update driver to a generic IDE controller.

If you have the DMA option box (in the device manager, hard disks, click on one hard disk, go to settings,) but it won't stay on or it degrades your computer's performance, you may have one of these problems:

- a bad or failing IDE cable on that drive
- misconfigured master/slave settings
- an incompatable drive which does not support UDMA (most above 2gigs do)
- an improper format or partition on the drive
- drive is not setup properly (or on 'auto') in BIOS

All audio software works best with DMA enabled on all drives, especially the audio drive. Pro Tools in particular must have the DMA box available and turned on for it to work properly.