Unliocking AMD Phenom II - have i broken it :(

Hi!

Well, I just got myself a new PC yesterday and I have broken it already. Basically the CPU is an AMD Phenom II x 2 550 Black Edition. Having read many eports online about unlocking the 3rd and 4th core I thought I would give it a go. My motherboard is an Asus M4N78 Pro (Nvidia Chipset so no ACC). Using the NCC option I was able to option up all 4 cores with a couple of key presses.

The computer boots fine into Windows XP and is stable whne web browsing and other light tasks. However, whenever I start a game it will lock in the first few minutes (2 symptoms: either BSOD or a system 'freeze'). Interestingly it just ran the Crysis Benmark test through 12 cycles with no crash (at 49 fps) - weird when its crashing World of Warcraft, COD4 and ARMA2 within minutes.

I havent tinkered with OC the CPU or graphics card. I have the latest Nvidia driver for my graphics card and the latest version of Directx9c.

My feeling is that one or both of the unlocked cores is probably a bit dodgy (but I am not expert in this field). In order to eliminate the possible faulty cores I need to turn them off again, ie. relock or disable them. How can I do this? I understand that it can be done with AMD overdrive ?? but that doesnt work with my MB chipset. I have tried all options that I understand in the Asus bios but I still end up with 4 cores (according to CPU-Z) and an unstable system.

Basic system details:
CPU: AMD Phenom II x 2 BE 550
MB: Asus M4N78 Pro (Nvidia 8300 Chipset)
Graphics: (stock) Sparkle GTX 275
Memory 2 x 2Gb Corsair DDR2

Have I damaged my CPU beyond repair? Am I going to have to buy a new one to get system stability back (I hope not because I have no money left after buying the new PC!)

Please help me if you can.

Regards

Richard

Attention idiots!!!!!!!!!!! The cores were locked for a reason!!!!!

Try to raise the vcore.