Computer reboots just after start

[GamerNurd]

Hi!
Processor: i7-2600K
Motherboard: MSI P67A-GD55
PSU: XFX 750W

I have raised my multplier to 40 and my voltages are on auto as they have been as default.
My question is why are my computer rebooting just after i pushed the start button, the first screen don't even show up. And after that reboot the computer are booting up just fine.

 

[scout_03]

overclock is to high .

 

[GamerNurd]

But after that reboot the computer runs just fine..Still the OC to high?
And the cpu-z still tells that the core clock is 4000Mhz

 

[scout_03]

did you also play with the memory settings .

 

[GamerNurd]

The memory settins is back on default 133xx somethins as it has been as default. But I did play with it before, but is back on default now
My RAM is Kingston Hyper X Beast 19200 2400Mhz

 

[scout_03]

did you memtest your memory also do you still on stock cooler and did you monitor your temp ,there is also a note for the 1600 memory speed and over in the motherboard user manual .