NOISE

The ALU iMacs have only been out for 8 months. Yes hard drives can get noisy as they age but you usually here the head seeking more than you would hear it humming. There are also 3 internal fans that you may be hearing. Try cleaning out the air vents on the bottom and the one for the Hard drive on the back right above the power cord. Try suction first then use a can of compressed air to blow it out.

George

Hi Andrew, download SMCfancontrol
http://homepage.mac.com/holtmann/eidac/software/page5/page5.html

and you can control the fans. Mine are set to be under 50ºC.
1432rpm
2220rpm
2572rpm

iStat pro shows the speeds of your fans

http://www.islayer.com/index.php?op=item&id=7

Message was edited by: musashi88

Hi Andrew

The Smcfancontrol works on my iMac. Looks like the same as yours. There seems to be no application just click on the menu bar (top of the screen beside the time)rpm to set speeds. Messed me up a little too.

If your fans are running during sleep mode either your computer is really hot, or it is malfunctioning. I seem to remember reading a lot about fans running when the computer is asleep. Abnormal. Take it in.

switching them off..not sure. check out your other temps. power supply position 1 is my hottest.

http://www.soft32.com/download_151429.html

You wouldn't want to switch them off completely. Use iStat Pro to see what the fan speeds are. The defaults should be something like this:

ODD: 1000
HDD: 1200
CPU: 1200

At the default speeds it should be very quiet. If they are running much faster than that you would probably hear them. If you want to test the fans for noise, use SMCFC and adjust one fan at a time. Keep in mind it takes a minute for the fans to adjust to the new setting.

George

Hi Andrew Davies1: Do you happen to have an external Hard Drive hooked to the iMac? I've noticed that my external causes what sounds like an ongoing low level hum. It lessens when I lift it slightly of the desk.

Stedman

Mine does not hum when it's in sleep mode. Everything gets powered down except for the RAM so I dunno what else it could be. Are you putting it to sleep manually? Could it be that the display is going to sleep before the system sleeps?

George

I'm getting much the same problem. iMac 3.06 24" was silent, not any audible sound whatsoever for the first month I owned it. Only when reading the HDD or CD/DVD did it make any noise.

Now the fan (I assume) is audible from across the room even when the machine has just started up.

smcFanControl doesn't silence it even when I slow it down as much as possible.

Am more concerned that something has come loose/broken after such a short time. iStat shows the fans running at around 1200 each. 😟

Bought a brand new iMac 24" 3.06GHz 4GB MEM 1TB HD 2 weeks ago.

Soft hum, but enough to go nuts.

Returned it, and today got a new one.

Same story.

I've read about this hum on different fora and ppl try to locate the problem.

But I noticed putting the system 2 feet from a wall actually solves the problem. Now that's great if your desk is in the middle of the room, but not the case here.

So this one's going back as well and I don't want another one.

I have a white 20" and a recent aluminum 20" model both are DEAD SILENT. No hum, no squeeck, nothing...

I think it's a serious flaw of the 24". At first I thought this new 3.06GHz processor needed some serious cooling but seems the 2.8GHz suffers the same problem.

If you install iStat Pro from www.islayer.com one can read the fan speeds.
1198-1200 rpm all the time and according to others it's same on both 2.8 and 3.06 models.

So I think Apple missed something here or they all have their pc's @ least 2 feet from a wall.

i have the same model, 3.06GHz 4GB memory. i hear a soft hum. i'm not clear about your 2 foot idea. do you think there is some resonance from the wall? can you explain a little more. thanks

Hmm weird. Mine's right next to the wall and likely to stay there...
Back it goes next week then, what a pile of poop.

Are the people on the other fora you're reading taking theirs back too? It seems trifling really, but is really annoying. Ta