Hi, im trying to OC my PC abit..

This is my comp spec:
Intel C2D E7400 2.80
Gigabyte EP41-UD3L(Intel G41 Chipset)
2GB DDR2 800MHz RAM
Gigabyte 9800GT 1GB GC
CM 550 Real Power PSU(19A on +12V rail)

This is how I did.
-Change FSB to 286(originally at 266MHz)
-Multiplier is 10.5, so my target CPU speed is 286*10.5=3003Mhz
-VCore is 1.2875(stock)
-Lowering SPD to 2.0

From my understanding, this FSB increase is very little and doesnt need any VCore increase..

To my concern, after I save settings and restart, my PC unable to boot at all..it just show POST half way then pufft..it turns off itself
Then restart automatically(this on-off process happens 2-3 times) until suddenly, it can boot properly but, this time FSB is back to normal(266MHz)..

What happened actually?Before this im using 450W psu with 230W real power also same thing happened. So i upgraded to CM psu.

PS: I tried increase VCore 5-10% but, same thing happen..