I have the Antec 900 with all the standard fans, and an added Thermaltake 120mm side fan. I run them all on the lowest settings and the system is very quite, while my temperatures are just fine. (E6300 overclocked to 3GHz, 8800 GTS overclocked to 600 core/2000 memory). I've run the fans on medium and high before, the system ran a little cooler, but the system went from being nice and quiet to sounding more like a jet engine!