It might be your CPU or the northbirdge...mine is weird..if I go above 152mhz, I get a bios protection error and it reloads all the defaults...I don't think it's my CPU because I can get it stable up to 1420mhz or so, but not at the 150FSB speed, so I run it at 1350. I prefer the higher bus speeds with slightly less mhz than a higher mhz and a lower bus speed..I like the memory performance at 150mhz..