Can only use 1 memory chip in my Asus P5N72-T

I have an Asus P5N72-T Premium (avoid it like the plague) MB, and Corsair XMS2 DHX memory 800Mhz. 2gig each (have 4 of them).
When ever I try to put in more then one chip, Vista 64 will lock up in minutes. It does no matter which chip I use solo, or which chip I try and add...it locks up. I have tried BIOS default, and 4-4-4-12-2T 2.1V ...does not matter. It is very stable with just one chip...no crashes yet.
What is odd is with all 4 in, Mem86 gives no errors even after 48 hours of burn in.

Other then taking a very large hammer   to this Asus MB, anyone have a less severe suggustion?
Asus will be of no use as this memory is not on their very short OVL.
Thanks!