I have an Intel Quad Core Q8200 processor clocked at stock speeds. My motherboard is a Gigabyte S2C G31
My idle CPU temps with stock cooler were always laundering around 50-55 C for all the cores. I just bought one of the best coolers in the market, the Gigabyte G-Power 2 Pro Cooler, and am seeing only 2-3 C drop in the temps. At 97% load with Prime95 my temps are between 60-65 for all 4 cores.
As long as the CPU temp stays below 71C, you should be fine. 60-65C is fine with Prime95 stress testing. My i7 920 stays just below 70C for the CPU and 75C for the 4 cores with HT/SMT on. According to this test, http://www.bit-tech.net/hardware/cooling/2008/07/06/gig... , the cooler actually does quite well on max fan speed. How high do you have the fan turned up? It doesn't do the best with the fan on 5V, so check the speed.