P4P800 Dlx DDR Dual Channel Mode Instability - Help?

Anyone know any reason why my memory would be less stable in dual channel
mode when it's perfectly stable in single channel mode?

System:
P4P800 Deluxe MB
P4 - 3.2 GHz processor
Corsair XMS TwinX1024-3200LL memory
WD Sata 120 GB boot drive
WD Pata 80 & 200 GB data drives on VIA controller
3 burners on primary controller
Radeon 9800 Pro 128
SB Live Value card
450 watt PS
Bios version is 1019. All settings are default except for disabled
Hyperthreading and disabled onboard audio.
Triple boot Win2K (x2) and XP from seperate primary partitions with
Bootmagic. Use XP for gaming only. Xp was even more unstable than Win2K
when running in dual channel mode.

When I run it in dual channel mode I get mysterious blue screen reboots with
messages like:
IRQL_NOT_LESS_OR_EQUAL or
PFN_LIST_CORRUPT or
KMODE_EXCEPTION_NOT_HANDLED
When it reboots from XP I will sometimes get some kind of hardware problem
message stating that it's shutting down to protect the system.

I've tried the ram in the blue and black slots. I've run single channel mode
in all slot combinations and either 512 stick by itself in all slots with no
issues. I wanted to buy another 1 gig set but am affraid it will begin
crashing again as it will be in dual channel mode automatically.

Thanks in advance,
RH

 

The datasheet from Corsairmicro, says the product is 2-3-2-6.
http://corsairmicro.com/corsair/products/specs/twinx1024-3200ll.pdf

Slide 24 of this presentation says CAS-tRCD-tRP-tRAS is the order
of the parameters listed above.
http://corsairmicro.com/corsair/products/tech/memory_basics/

You can check the basic settings of the hardware with:
http://www.cpuid.com/cpuz.php

And can get the free memory test tool memtest86 from:
http://www.memtest.org

Memtest86 is a tool that you load onto a blank floppy, and it
boots the computer. It is also available in an ISO version for
burning on a CD (if the computer doesn't have a floppy).

I would start by entering the BIOS, and setting Vdimm voltage
to a level useful for high performance memory. At least 2.6V
is needed (as seen on the memory chip makers datasheets) and
a value of 2.75V help a bit, without endangering the memory.
Too low a voltage is a frequent reason for seeing errors.

Also, while in the BIOS, make sure you aren't using any
settings like "Turbo" or "StreetRacer" and the like, as
some of these enforce a 2-2-2 memory setting without actually
verifying that the memory can handle it.

Boot into Windows and use CPUZ to verify your processor and
memory frequencies. You can use CPUZ to tell whether the
FSB is FSB800, CPU core 3.2GHz, memory timings 2-3-2-6 and
so on. CPUZ will tell you whether you've set up things at
normal levels, or are severely overclocking something by
accident.

Reboot the computer, and use the memtest86 boot floppy to test
the memory. Memtest86 is a self contained boot program, and
doesn't need DOS. The memtest86 program will format the blank
floppy for you - the floppy won't have a normal file system
on it, after memtest86 formats it for you, but the floppy
will boot the computer just fine.

A little more voltage could be enough to fix it. Changing the
memory timings, to something a little more relaxed, like
2.5-3-2-8 might help as well. Now, for many people, this
would be a signal, that they need to RMA the memory. You
may find that one stick is OK and the other one has errors,
in which case it will be more obvious that one stick could
use an RMA.

If you cannot get enough help here, the Corsair support
is over here:

http://www.houseofhelp.com/forums/forumdisplay.php?forumid=128

HTH,
Paul

 

Ok,
After much fiddling about I've adjusted the "AI Overclock Tuner" from
standard to manual. This has allowed me to manually set the DDR voltage to
2.75v. I set "Performance Mode" from Auto to Standard (It was never set to
Turbo). Don't know if that really helps. Configuring the DRAM timings
manually had little effect. DRAM timings were properly configured by SPD
and CPUZ verified settings as 2-3-2-6. Memtest errors dropped at 2.65v and
more so at 2.75v. I still recieve some errors now that I'm running it back
in Dual-Channel mode (14 in test 5 and 5 in test 7 after four full passes)
but no crashes or instability that I can tell. And relaxing the timing does
not decrease the errors. Good call on the voltage. Should I be concerned
that I'm not getting squeky clean test results from Memtest?

Thanks,
RH