New Build NO POST

["Nick Le Lievre"]

I just put together the following;

e6420
4GB RAM (although only 1 stick in at the moment)
Gigabyte P35C DS3R
BFG 8800 GTS OC 320mb

At first when I connected all the case wires to motherboard I had no 
power... then I removed all the wires and just placed the power switch... 
now I get all fans spinning up but NO POST and no sound from the speaker. Do 
you think I should take a look at the CPU mounting... I placed the CPU in 
the socket correctly (I think) and put the metal bracket over it and locked 
into place then mounted the heatsink....

Whats the easiest way to remove a socket 775 heatsink... its got the push 
pins.