I have 4x1GB Sticks, so all slots are full.

I am just curious though, would the "hang" be related to DRAM settings, or is that still voltage? I'm beginning to wonder if I should just be happy with 3.6GHz and not try for 4GHz. I need a 100% stable system. I figured with 3x120 water cooling I could do the 4GHz, but I'm having so much instability when I try it out...