I've found issues with the memory dividers causing stability issues with my overclock. I managed to get 3.8 prime stable, but when I game it will still crash on me. Dropped my memory to 1:1 and it's always fine. Running 4GB G.Skill DDR2-1100 which is memtest stable, so it's not the ram, but the divider on the board.

I've tried the latest bioses for P5K-E but the 0602 seems to be the best still.