Gigabyte trouble

I have a GA-P35-DS3P. I had my E6600 up to 3.6 with this board and was just doing minor stuff to test temps before I ran prime95. Everything seemed to be working fine until I ran the test. I lost the first thread in under a minute and the second thread a couple later. Figured the problem was voltage and raised CPU to 1.4 same thing crash. Raised the FSB .1v and again same thing. So I raise north bridge .1 volts and again same thing! Decided that I was going to have to be alot less aggressive and backed everything off. Decided to l'd try again to day and the board wont let me change the frequency for the cpu at all. It will let me change the ram. It looks like everything is fiene in the bios and even askes do you want to save changes to cmos. I choose yes like always and when system reboots the cpu is renning stock with no changes! I am really confused. Would appreciate any suggestions