Been concerned that my iMac C2D 20 inch has got noisier since I got it last month. Putting my head close to the screen I can hear a faint hum. Some people have said this is to do with the screen brightness but not in my case. At the back it is really noticable and like my old PC. I've wondered about the firmware upgrade I did or possibly some sort of hardware problem developing. So I loaded smc Fan Control and iStat Pro desktop widget. By using SMC to increase fan speeds and looking at iStat I found the following:
Fan 0 ODD 800-5000 rpm (min and max)
Fan 1 HDD 1400-5000 rpm
Fan 2 CPU 800-3600 rpm (exhaust vent just above power cord)
Normal operation is F0 800, F1 1400, F2 800. Turning up the fans gave that fasten your seatbelt feeling, The CPU is the nastiest noise but clearly a fan, nothing sinister. Anyone else got some figures to compare?
When I first got my iMac I was stunned by its quietness. I could actually hear hard drive seeks and got panicky about that until I realised I had a Western Digital hard drive (not a Seagate - previous bad experience).
I think for me the noise has not changed I am just getting really picky. Once the initial WOW wears off you listen out more. A real problem is always obvious and it sounds like some people have real problems. The rest is just worry. Its quieter than my Toshiba Portege and I hope it stays that way!
I've got a 20in 2.16GHz Core 2 Duo system that I bought in Dec 06. One thing I would NEVER describe it as is whisper quiet.
I wish it were that way, and I'm always astounded when people say that.
I work in a very quiet home office. I can definitely hear the fans and also the hard disk. The whole system is quieter than virtually every other computer I've owned (apart from notebooks), but it's not silent. Right now I can hear the fans and the hard disk pretty clearly, and I'm just sitting at my desk. It's a slightly annoying, laboring-type noise.
My fan speeds are 831 (fan 2), 1398 (fan 1) and 797 (fan 0), according to iStat. Note that iStat might not yet be tuned for 20in iMacs C2D, although I understand they recently added support for 24in C2D iMacs.