CPU overclocking

[cera25]

HI everybody, I have an ecsgf8200a motheboard with the bios upgraded, my cpu is a Phenom II X4 955 BE, normally the cpu runs well, with no problem, when I overclock the cpu and save the configuration on the bios, the pc restart is ok and runs perfectly, but when I shut down the pc and start it again the windows doesn't start, just black screen.
What could be the problem?
Thanks

 

[boabs]

one its doesnt go on when ya go back into bios and default the settings uve just chanfged does comp work again.?

 

[cera25]

yes

 

[cera25]

I have to reset the pc to boot normally