Overlocking Intel Core 2 Quad Q9550

[Seudral]

I've got a Dell motherboard 0G254H with a Dell X48 chipset. I was wondering, how much can I overclock my Intel core 2 quad Q9550 - currently at 2.83GHz?.
I've got an incredible passive cooling on my CPU ( 2 months of non-stop gaming and didn't even heat up a tiny bit - as much as I know )

I use 8GB of DDR3 ram if that's important since i'm new to overclocking.

 

[cin19]

Sorry, you can't oc the cpu on the Dell PC, because they locked the overclock feature.