I have an Asus Rampage II Extreme which I would assume must be very similar to the P6T. With the stock fan I can get my i920 to a Bclock of 160MHz. I raised the CPU voltage to 1.4V but this did not really help.

I have a Mach II GT cooler which cools the CPU down to -50C. Under a 200W load it goes up to about -10C. The thing is that colling the CPU did not change the Bclock performance. I was still only able to get a Bclock of 160MHz at -50C. Once I had the CPU at -50C I also raised all of the CPU voltages to their maximum safe settings (core voltage at 1.5V) but this did not help.

I am assuming that it is not the CPU that is holding me back. I reduced the memory speed so as not to exceed the rated speed of my memory so that is not the issue. Can anyone give me any pointers?