P5E WS Pro + XMS2 CM2X2048-6400C5C. Unstable with four sticks of RAM.

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A while ago I purchased 2 sets of XMS2 CM2X2048-6400C5C (4 Sticks), to upgrade my Wife's Q300+Asus P5E WS Pro board. However, upon installation we had an almost immediate failure of one set with multiple errors and BSODs and soon after the system would no longer post. I tracked down the faulty set and sent it back for a replacement part. In the meantime the good pair has been working flawlessly.

I installed the replacement set a couple days ago, which brought the system from 4 gig to 8 gig of RAM total. However, the system started having multiple graphics driver and explorer crashes soon after. At first I thought they had sent me another faulty set, except upon testing and lots of swapping back and forth and various tests, I have determined that both sets will work fine when installed as single pair (2x2048), in either primary or secondary RAM slots, but once all RAM is installed (4x2048), I once again get video driver crashes and explorer crashes.

When configuring the RAM for the first time, I did learn I had to manual set memory speed to 800 and the voltage to 1.8 or the system isn't stable. The system usually runs 2.5@3ghz 400FSB, 333 strap, RAM 800mhz 1.8v. A fairly simple OC, that runs 100% stable through any test I could throw at it (and has done so for nearly 2 years).

Currently the system is running default clock speeds for testing (333 FSB, 667 Ram, 1.8v), however, even at default speeds, it still wont remain stable with all 4 sticks installed.

I'm wondering if anyone has any explanation as to why this could be happening and suggestions on what to do next.

Thanks in advance.

 

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I managed to get it apparently stable just by increasing the NB Voltage to 1.31. Anything under or over that was a no-go. I still had to set the RAM manually to 667Mhz 1.8v and set timings to manual. Currently it passes all tests at default clock speeds.

With those results I got a little eager and tried putting it back to the usual OC of 3ghz/400, and playing with voltage of RAM and NB. While it passed Memtest fine with two passes, it failed when running 3D mark. I'll give it a few days running at default speeds, then attempt to get the OC once again with a bit more tweaking.