the problem:
when trying to enable DMA in windows XP
(Device Manager: IDE ATA/ATAPI controllers -> Primary/Secondary IDE Channel -> Advanced Settings tab -> Device 0/1, Transfer Mode pull-down menu, choosing "DMA if available".
for detailed instructions look here: How to enable DMA in Windows XP (with pictures))
windows refuses to enable DMA, stays in PIO mode.
a possible solution:
to uninstall that IDE channel (right click Primary/Secondary IDE Channel -> Unintsall)
BE VERY CAREFUL your OS drive isn't on the channel your'e uninstalling!!!
then scan for new hardware (Action -> Scan for hardware changes), and let windows redetect and reinstall the IDE channel and the devices on it.
usually after this operation selecting "DMA if available" enables DMA.
Note:
some members of the forum reported that it is possible to uninstall the IDE channel on which the OS drive is located without problems. after doing so windows asks for a reboot after which it redetects and reinstalls the IDE channel. i have'nt tried this myself (yet) though. so do it at you own risk.