Overclocking P55 With 4 DIMMS

[ta2]

Had a nice stable overclock of the following:

i5 750 @ 20x200
2x2GB @ 2000MHz CAS9, 1.65V

Added another 2x2GB of the same sticks (which are rated up to 2133MHz CAS9). Got a BSOD straight away so went back down to stock speeds. I'm now running at the following, but it's still a little shaky:

i5 750 @ 20x200
4x2GB @ 1600MHZ CAS7, 1.6V

The memory SPD is rated at:

1333, 7-7-7-24 @ 1.5V
1522, 8-8-8-28 @ 1.5V
2133, 9-9-9-28 @ 1.65V

Are the SPD settings a little too tight when using 4 DIMMS, should I just lower the timings on the memory a little bit? Is there any disadvantage to running the DIMMS at a low frequency (say 1600MHz) at their rated max of 1.65V other than heat/power requirements, even if they don't require that much? Obviously that would be just for testing purposes.

Cheers!

[Flewis]

Have you upped the northbridge voltage. An increase is usually required when moving to 4 dimms

[jim]

You'll always struggle with 4 DIMMs, and AFAIK raising the northbridge voltage as mentioned previously is the only thing you can do, although it doesn't solve the problem.

2x4GB matched DIMMs are the answer, although maybe not just yet.

[Pob255]

Have you upped the northbridge voltage. An increase is usually required when moving to 4 dimms

P55 = What north bridge?

[ta2]

Do you guys mean the QPI/VTT voltage? What's a safe level for that, I think I'm on 1.1V at the moment.

[nibbler]

VTT is the memory controller. I think you should be safe at 1.3 (they did it in customPC...)