Here is my latest stable.
http://img509.imageshack.us/img509/379/4gzco3.jpg
I kept getting a failure after 2 - 2.5 hours and my games would crash but not BSOD windows. I remember in a previous post in these forums that someone mentioned bumping up VTT a notch or two to provide stability. 1.16 VTT and the proper gtl refs fixed those crashes and 8+ hours and counting.
I still need to tweak out my ram for sure and also push the cpu harder but i'm pretty happy with getting 4ghz stable so far.. shesh it's took a long time.