Help Overclocking a Q9550

I am a noob at overclocking, all I have overclocked was my old q6600 to 3GHZ.
MY PC:
CPU - Q9550
Cooler - Zalman CNPS 9900 LED
GPU - XFX 4870 XXX
Motherboard - Biostar T-Power I45
PSU - Corsair HX650
RAM - 2x2 GB OCZ 1066mhz Blade series

My CPU runs at 31C under load and my GPU runs at 50C
I can't reach past 3.1ghz without my computer crashing. I am not sure what I am doing wrong.
Please help if yo can.