There is a clue to the problem here:
http://www.digital-daily.com/motherboard/ati9100igp-asus-giga/index04.htm
The problem relates to the BIOS design. There are no user
accessable memory settings, unlike the Gigabyte board compared
to the Asus board. I do not recommend the purchase of motherboards
that do not have extensive DRAM settings in the BIOS - steering
the operation of the BIOS by buying PC2700 RAM, is a stupid way to
do things.
The manual hints at the problem.
******
Dual-channel (1) Populated x Populated x
(PC3200) (Single-sided) (Single-sided)
* This motherboard supports one single-sided PC3200 (DDR400)
DIMM per channel only.
* This motherboard may only detect PC2700 (DDR333) system
memory when you install two PC3200 (DDR400) DIMMs in one
channel or when you install double-sided PC3200 (DDR400) DIMMs.
******
The first thing I would do, is get a copy of CPUZ from cpuid.com.
(I don't know if Everest Home Edition, from Lavalys.com would aid
in this job or not. It is another utility you can get for free.)
Install your working single stick. Boot to Windows, run CPUZ, and
get all available info about the RAM. It might tell you PC3200
2-3-3-6 or the like.
Now, get a copy of memtest86+ from memtest.org . It will format a
blank floppy for you, and makes a self booting test (no OS required).
Boot the memtest86+ floppy and test the original memory stick.
Do a couple of complete passes error free, before concluding
that stick is good.
Next step, is shut down and install the new stick of memory.
Run memtest86+ on the new single stick of memory, and see if it is
error free for a couple of passes. If you are getting errors,
take the stick back to the store and get your money back.
Assuming the stick tests good, it is safe to boot into Windows.
Run CPUZ and collect the vital statistics on the RAM.
If both of these DIMMs are double sided 512MB memory (a very common
form of construction), it could be that the BIOS is having trouble
downclocking the memory to DDR333. At least, based on the description
in the manual, that is what it appears is supposed to happen. If
the two DIMMs have different nominal timing, maybe the BIOS is getting
confused and craps out before achieving that setting ? (A Gigabyte
user manual I looked at, suggests the chipset is flexible on memory
clock rates, and if the chipset wants to, it can support DDR200,
DDR266, DDR333, DDR400 memory clocking. So, this doesn't appear to
be a limitation of the hardware.)
Now, the question is, what to do if both DIMMs test good individually,
but not together. Does the computer pass POST (power on self test) ?
In other words, dues it get to the point of accessing the disk ?
Or is it just a dead black screen ? If the two sticks are not matched
in terms of the timings in the SPD of the DIMM, maybe that is enough
to confuse the BIOS - normally a BIOS selects the slower of the
two timing specs, and uses that to set up the CAS, tRCD, tRP, and so
on.
You also have two placement options for your two DIMMs. You can try
running them in A1&A2 (single channel) or A1&B1 (dual channel). I
suppose, if this is a timing confusion bug in the BIOS, it will fail
in both cases.
Some options - (2) is the lowest risk, but it sucks as a choice.
1) Match the sticks. Tough to do if the store doesn't have the
exact same part number. Matching the sticks may please the BIOS or
it may not.
2) Buy 2x512MB PC2700 (DDR333) memories. The BIOS will not try to run
them at DDR400, so there are fewer potential gotchas. By matching
them when you buy them, again, less risk that the BIOS gets hung up.
3) Try 2x512MB PC3200 matched double sided memories, on the premise
that by matching the memories, perhaps the BIOS can get past whatever
bug it has got. This is only better than your current situation, in
that the timing in the SPD of each DIMM is exactly the same. This is,
after all, supposed to work at DDR333.
4) Find the more obscure 2x512MB PC3200 single sided memories. That
meets the manual's requirement of using single sided memory for
this. I had a quick look, and cannot find any. It may take
quite a bit of searching to find some (I know they are out there).
You can see here, that at least Crucial thinks both PC2700 and
PC3200 are supposed to work.
http://www.crucial.com/store/listparts.asp?model=P4R800-VM&tabid=AM
Have you tried upgrading the BIOS ? I only see one BIOS that mentions
anything to do with memory. But perhaps that will be the key to getting
better behavior. Click the "BIOS" button:
http://support.asus.com.tw/download...product=1&f_name=&type=Latest&SLanguage=en-us
I guess according to these two threads, you are not alone.
"P4R800-VM + DUAL Channel"
http://www.abxzone.com/forums/showthread.php?t=66256&highlight=p4r800-vm
"Asus P4r800-vm"
http://www.abxzone.com/forums/showthread.php?s=&threadid=61383
Paul
