Obviously these are spectacular results. At no moment we reached critical temperatures, not even at 4GHz. This is truly remarkable since the Intel Core i7 920 can be run at 80°C – 85°C without risking anything.
Also, remember that I used software which loaded all four cores to 100% simultaneously. In reality this will almost never happen. Therefore these maximum temperatures are truly the extremes.
The results point to the conclusion that the gains by using two fans are minor. I actually found the Scythe Gentle Typhoon fans to have a great balance between cooling performance and noise level at 1450RPM.
As a little curiosity I also ran the CPU at 3.4GHz without HyperThreading enabled. The result was quite significant. With the HT activated the average temperature was 63°C, with HT deactivated the average temperature was 56°C, which is considerably lower….