So you used a different processor and it worked? But with your chip it doesn't?
I'd make sure the fan and heatsink is correctly seated onto the cpu with some fresh thermal paste.
You say the GPU fan isn't spinning at all? Remove it from your board and use standard vga port and intel hd 3000 graphics.
Have you got the 8pin connector plugged into your motherboard as well as the 24pin connector?
Put the motherboard, cpu heatsink and fan, hdd onto a cardboard box and try booting, might be shorting on the case.
Try using one stick of ram in slot #1, if it doesn't work, use another ram slot, or another ram stick.
Remove all non necessary parts like gpu, dvd drive etc.