Why wont my computer start?

Hey guys,

I recently bought an xfx radeon hd 6850, after installing it i turned the pc on and all i saw on my monitor was 'Digital power saving mode'. When i start the computer all the fans turn on but i hear no start up bleeps or anything, even the mouse and keyboard wont turn on!
I left it running for a bit and after about 20 mins i hear the computer starting up but still the monitor wont turn on, so i switch to my on board vga and the screen turns on.

WHAT THE HELL IS GOING ON?

~SPECS~

:XFX pro 650W psu
:AMD athlon II x4 630 2.80 ghz (oc'd to 3.10)
:4 GB DDR2 RAM
:ASROCK k10n78fullhd-hsli
:Seagate barracuda 7200 rpm 500GB HDD
 VD/RWD

Also when looking in device manager the card does not show up.

Thanks!