The current stock fan on the spare PC is making an annoying whirring noise so want to replace it. Looking at the specs for the AMD Phenom II X4 840 it looks like its a 2.75" fan which is approx 70mm but i cant seem to find a 4 pin fan at this size on the site. Can anyone recommended a replacement cpu fan that has 4 pins and will fit on the AMD Phenom II X4 840 heatsink?