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Enable DMA?

SimonInd

Standard Member
Whilst investigating the cause of tearing on my new HTPC I found that DMA is not enabled for my DVD drive and this is obviously partially causing the problem. The IDE controller is set to 'DMA if available' but the NEC 3450 DVD drive is not playing ball. It's the slave on the primary channel, the master is a CD-Rom drive ( the HDD is SATA ).

Do I need to switch the two drives to get DMA working? or is it a problem with the drive or it's drivers?

Cheers

Simon
 

KraGorn

Active Member
Have you been experiencing media errors on this drive? XP has a 'helpful' (sic) feature whereby if a drive starts to log many errors it drops back to PIO mode and won't revert to DMA. You need to fiddle with the registry to make it forget them, or else uninstall the drive, disconnect it and reboot. Then re-connect and re-boot and it'll think it's a new drive.

If this doesn't sound like a scenario that's relevant I'm not sure what to suggest. I have 2 burners on the same channel and both are working fine in DMA. I suppose it wouldn't do any harm to swap them round, that'd do the same thing as I was just suggesting so you'd not have anything to lose.
 

SimonInd

Standard Member
I haven't seen any errors, although AnyDVD often complains when a new disc is inserted but then acts normally. This may be a result of the DMA being switched off or errors on readin the disc I guess?

I'll try uninistalling and re-installing tonight as that should be quick and painless, if not then I guess I've got a dodgy drive...

Thanks

Simon
 

SimonInd

Standard Member
Thanks guys, I disabled, then uninstalled the Primary IDE controller ( there's only one installed as the HDD is SATA ), re-booted and after a minute or so XP recognised the controller, the CD-ROM and DVDRW drives. I then had to set the controller to 'Use DMA if available' for each drive and re-boot but all is now well. Tearing has disappeared and I'm back to using about 30% of a hyper-threaded CPU with FFDShow.

Cheers

Simon
 

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