I am having some weird issues trying to OC with 12GB on this board and was wondering if anyone could give me some advice:
i7 920 D0 @4.22Ghz
6x2GB Corsair DDR3 1600 (CM3X2G1600C9)
BIOS 407

Current stable BIOS settings:

Multi: 21x
Base Clock: 200
RAM: DDR3 1203
Vcore: 1.35v
vQPI: 1.65v
VDimm: Auto

If I set my vDimm off auto, I only detect either 8GB or 10GB of the RAM at boot up depending on the other settings. If I set the RAM speed at anything above the lowest value, I can't get more than 8GB to detect on boot up. I've tried manual vDimm values from 1.5v all the way to 1.7v, but it still won't detect all of my RAM like the auto setting does. I've tried using both the XMP profile and straight manual overclocking, but it doesn't seem to affect the result.

Any ideas on what else I can try?