Re: DMA settings?

Tech-Archive recommends: Fix windows errors by optimizing your registry

"Gary Fritz" <fritzxxx@xxxxxxxxxxx> wrote in message news:Xns980A8978D50F2fritzfriicom@xxxxxxxxxxxxxxx
"Glen" <nospam@xxxxxxxxxxxxx> wrote:
Just from my own experience this change occurs either because
of flaky hardware (Windows does a bus test every time it boots,
and if any part of the IDE chain (devices, cables etc) fails a
DMA transfer test it'll revert to PIO mode), or poorly written
IDE and/or chipset drivers (e.g. older mainboards with Via and
Apollo chipsets are notorious for this).

Umm. That makes sense. It's certainly possible the hardware is flaky
-- it's a no-name DVD-RW from Best Buy. The mobo is an Asus A7V266-E
with Via chipsets, but I'm 99% sure I have the latest drivers.

Presumably if the DVD-RW failed a boot-up test, the system records that
in the registry and never tries again. If the DVD-RW is iffy, it would
be simple enough to clear the DMA-failure flag any time Windows decided
it didn't like it.

OK, I dug around in the registry for a while without finding any obvious
answers. Then I went hunting on the web again, and hit paydirt:

http://winhlp.com/WxDMA.htm

This site describes this exact problem. It's aimed at XP but it says it
also works for w2000. As described about halfway down on that page, I
went to HKLM\SYSTEM\CurrentControlSet\Control\Class\{4D36E96A-E325-11CE-
BFC1-08002BE10318} and found my secondary IDE channel. I deleted
MasterIdDataChecksum (there was no SlaveIdDataChecksum since I have no
slave device on that channel) and rebooted.

Shazam! My DVD-RW is running UDMA again!

Apparently this problem can be triggered by something as simple as a
scratched CD or DVD. Lovely that Windows decides to permanently disable
DMA just because of a media problem. But at least now I know what's
causing it and how to fix it, without reinstalling anything.

Thanks for pointing me in the right direction!
Gary

Ur welcome. You might want to double-check for
updated Via drivers even though the issue is resolved.


.

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