Overclocking Q6600 question

[Pokopo]

I have a Hackintosh with Bad Axe 2 and Q6600 quadcore running smoothly

 

I wanted to overclock it a bit but everytime I change any performance settings in BIOS, it won't let me boot. It forces me back to the BIOS settings. If I change anything else, it's fine but if I try to change performance options, it either reverts to old settings or goes back to BIOS..

 

Any help would be appreciated.

 

Thanks.