My macbook has been running quite hot recently, the fans are fire up about 10 seconds after booting up and never go off. temperatures are around 70ºC with no apps running. running Top and Activity Monitor reveal nothing using much cpu (top and activity monitor are at the top of the usage list and neither is using more than 4-5% cpu), and total cpu load is around 5%. I installed a fresh copy of leopard on an external drive and found the problem disappeared, so it's definitely a software issue. booted of the external drive I was able to run the laptop for over an hour without it getting hot to touch, and the fans were inaudible. I use the "Better Energy Savings" energy profile, with the only change being that I set it to never put the computer to sleep. the only way I can think of that the thing would generate so much heat while doing so little would be if the cpu wasnt throttling itself properly, but I dont know where to look to see if that's the problem. Can anyone tell me what else I should try? I dont think I should have to reformat the notebook to fix this.