lga775 to 771

Hi, what is the best cooler for the Q9550? I want a cooler that can cool the Q9550 with no issues at all, and I am planning to overclock it to 3.6 GHz and higher! Specs: Case: DELUX ATX Mid-tower BMW style case CPU: Q9550 clocked @ 3.6 GHz (wanna go higher) (Planning to get a Xeon E5450)...

I just bought a CPU Xeon x5450 Lga 771 with the mode already done so i can just put the CPU inside the Lga 775 motherboard. When i turn on the PC the fans spin, but monitor is showing no signal! Please Help!