UDMA mode 5 for HD's is pretty common as is UDMA mode 2 for optical devices..
on the same IDE channel showing UDMA mode 5 for both drives. If you manually
set them to UDMA mode 6, there en lies the problem..
Post by DougCuk
I have also been battling a problem with XP SP2 showing sporadic IDE
Hardisk errors in the system log and also falling back from UDMA to PIO
The driver detected a controller error on \Device\Harddisk0\DR0
An error was detected on device \Device\Harddisk0\DR0 during a paging
\Device\Ide\IdePort0, did not respond within the timeout period
Various "Delayed Write Failed" errors
After a long process of testing I think I have found the root of the
I was attempting to run two ATA UDMA6 drives on the same IDE cable -
Master drive: Samsung 40Gb SP04011N
Slave drive: Maxtor 80Gb Diamond Max 9 (also tested a new Maxtor
With both drives set to UDMA6 the Samsung reports sporadic UDMA CRC
errors recorded by the drives SMART system and XP records sporadic
bursts of Disk conroller errors in the System Event Log. The HD's SMART
data can be viewed in Windows using various utilities - I used SpeedFan.
After a while XP implements a protective UDMA fallback for the affected
drive and ends up at PIO mode.
To eliminate possible driver problems I tested the drive and cable
setup using using the SpinRite HD testing program from Gibson Research
(www.grc.com) - this runs from pure DOS but can test NTFS formatted
disks - so if the problem still appears its not caused by Windows
drivers or registry settings. SpinRite reported sporadic UDMA CRC
errors (cabling errors) from the Samsung HD with the BIOS set to UDMA6.
I tested an identical Samsung HD, and tried many different IDE cables
without success. Finally I tested the Samsung HD on its own without the
Maxtor on the cable - the fault vanished. I then restricted the Samsung
to UDMA5 in the BIOS and retested the dual drive configuration - the
fault had vanished. The Samsung runs fault free at UDMA6 as long as it
is alone on the cable - but tests with two different UDMA6 Maxtor
drives as Slave devices always caused the Samsung to become unstable at
UDMA6 - reducing the BIOS setting for the Samsung to UDMA5 restores
It appears the two drives have some kind of conflict that causes a
corruption of the UDMA data when attempting to run at the full UDMA6
speeds. The errors are at a very low density and do not generally cause
any data corruption - they just cause the drives and Windows to
sporadically record controller errors. Unfortunately the standard
registry settings in XP SP2 trigger a UDMA speed fallback after 6
cumulative errors - often resulting in a rapid drop back to PIO mode
from a single burst of controller errors.
Having eliminated all other causes and being able to switch the fault
on and off at will - I am forced to accept that the Samsung will not
run at UDMA6 when paired with a Maxtor UDMA6 drive. The final test
would be to try testing it paired with another Samsung drive and see if
it works in that configuration.
Note: As a safety measure XP blocks all attempts to reset UDMA for the
affected drive to protect data integrity. And until you have eliminated
the cause of the errors it will after a short period just revert back to
PIO mode each time you reset the required registry settings.
Once the controller errors have been eliminated you have to deleted the
affected IDE controller in Device Manager and reboot to reinstall a
clean copy of the registry settings. Or you can hack the registry as
stated in the previous forum post to reset back to UDMA mode but its
Hope this lengthy report is of some assistance to others with a similar
type of problem.
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