Memory Problem With P5w-dh

Hi all,
I have a little brain teaser here, I have a ASUS P5W-DH with a intell Quad core 6600, antec true power 650 watt psu, latest asus bios applied,

firstly I installed 2 crucial ballistix 8500 dims, bios dont auto detect correct speed, so I set it mamually, and everything was fine. anyway then I decided to upgrade my op system to windows ultimate 64 bit, still every thing is ok.

the problem starts when I then added another 2 gb of crucial ballistix same speed as others giving me a total of 4 gig.

what happens now is reboots or blue screen, the pairs are different batches, but crucial, assuure me they are the same density and are compatable.

They will run stable at PC7100 SETTING, so why not 8500? yet stable as pairs, even if I mix batch numbers, 3 will run ok, I am thinking voltage's have tried 1.95-1.80-2.0-2.05-2.2 and 2.15 to no avail, anyone had similar problems.

2GB kit (1GBx2), Ballistix 240-pin DIMM, DDR2 PC2-8500 memory module
BL2KIT12864AA1065






Module Size: 2GB kit (1GBx2)
Package: Ballistix 240-pin DIMM
Feature: DDR2 PC2-8500
Specs: DDR2 PC2-8500 • 5-5-5-15 • Unbuffered • NON-ECC • DDR2-1066 • 2.2V • 128Meg x 64

Put the new pair in and remove the old pair. Does it still bsod? Crucial are great, but occasionally you can get the odd bad stick which they will replace with flurries of apologies.

Check Asus website for memory compatibility list and email them with this problem... maybe they need to update the bios again... by the way, did you check for beta bios?

Any pair, in any combination, even 3 will run perfect, add fourth and it gos terrible, any combination of 3 which rules out faulty stick, thats at 1066 mhz, PC 8500, IT WILL RUN FINE IF i set it to PC7100:mad: , BUT WONT DO 4 STICKS AT 8500, I suspect voltage, have now tried2.4-2.35-2.30 and 2.25 to no avail, it will run at PC7100 on auto setting:confused: ,

I hate to break this to you, but the memory spec for the motherboard is

Quote:

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Dual channel memory architecture
4 x 240-pin DIMM sockets support max. 8GB DDR2 800/ 667/ 533 ECC and non-ECC memory
Intel MPT (Intel Memory Pipeline Technology)
ASUS Hyper Path3

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The CPU can run at 1066, but not your RAM

With unbuffered memory, it's not unusual for a board to be unable to run the memory as fast with all slots filled. The memory controller doesn't have enough drive current available to handle the capacitive load at the higher frequency.

Looks like I need a bios update from asus maybe, the crazy part is the setting is in the bios, and 2 gb will run at 1066 mhz no problem:rolleyes:

Do you think if I got 2 2gb sticks it may be ok?

If it's a capacitive loading problem, using 2 x 2GB DIMMs may well solve it. The system specifications or motherboard manual sometimes mention if there is a speed consequence to filling all slots.

Just to conclude this thread I am settling for the PC7100 SETTING WHICH IS TOTALLY STABLE, I can confirm 2 x 1gb will run at PC8500, IF ANYONE TESTS 2 X 2GB STICKS WOULD APPRECIATE THHE RESULT.