I've recently noticed that my 2008 24" iMac is noisier than before. iStat shows the CPU fan at 2000-2500, and some seemingly hot temperatures - measured with minimal activity. ---------- Ambient Air 26°C CPU A Heatsink 51°C CPU Core 1 56°C CPU Core 2 55°C Display Screen Proximity 51°C Graphics Processor Chip 1 68°C Graphics Processor Heatsink 1 68°C Graphics Processor Temperature Diode 74°C Hard Drive Bay 1 54°C Main Logic Board 55°C Optical Drive 48°C Power Supply Position 1 82°C Wireless Module 56°C ---------- I know they can often run hot, but don't know enough to decide if there's a potential problem here. I installed smcfancontrol and bumped the speeds to successfully lower the temperatures. But that caused an unwanted problem... on trying to return the speeds to default they remain high - and only by a reboot can I get them down. Having reset the SMC, I now have speeds of 700/1200/1800 (OD/HD/CPU).