iMac making loud fan noise
It's a 2007 Intel Core2 Duo iMac7,1 2.4GHz. It's less than six months old and has just been back to the Apple Store for repairs.
It now starts to make a very loud fan noise: CPU Drive 1200rpm, Hard Drive 1200rpm, Optical Drive 100rpm.
Then the CPU Drive fan goes up to 3400rpm.
I have tried resetting the SMU and also removed power and USB cables, waited and restarted. It still makes loud fan noises even while doing low performance tasks like writing email or browsing the web.
iMac, Mac OS X (10.5.2), 2007 Intel Core2 Duo 2.4GHz iMac7,1