Ga-k8nsli & fx55

I just did an upgrade on the CPU front. Opteron 144 (2.5GHz) to an FX55
(2.6GHz).

Now when I try to overclock the FX all fails. Even simple things like ratio
13 to 14 causes the usual BSOD. My Opty 144 just worked but this thing dies
no matter what I try.
Am I missing something . Is it a CPU issue or mobo though the opty did take
a bit of persausion it did work but no matter what I do it BSODs
XP vs Vista64 doesnt matter, it's the same for both. My 3dmark 06 score is
suffering 6200 - 5320 with the FX (???)
2GB DDR400, 600W PSU, Arctic Cooling freezer64 Pro, HD2900XT vga card.

Robin