Random high speed fan issues on iMac

[smiffy121]

Hi,

I've had my iMac for over a year and on random occasions the fan turns on even when it is on standby. It makes a tremendous noise and is only solved by turning the thing off.

Does anyone know why this happens and how to stop it occurring.

Thanks

[Sirus]

I know this is pretty late....

Try downloading smc fan control, it controls the fans using software. You can see all the info about fan speed and system temps in dashboard when its running.

Just set your fans to be at about 2000 rpm's or higher/lower depending on what you are doing or the noise level you can tolerate.

Maybe your temp sensors are screwing up and making the fans speed up.... you will be able to see if this is the case in smc fan control as it gives you the readings of the temps too.

SMC should help stop the fans from taking off whenever they want..... but remember, DONT turn you fans rpm's too low. The heat build up may damage something because the normal software wont kick in and make them speed up.. you will need to keep an eye on things because with smc you will be in control of the fans... 2000rpm or slightly more should be good for cooling and still be quiet too.

EDIT- Actually its iStat that will give you the dashboard reading of temps etc... get that widget, so to keep an eye on temps when smc fan control is running

[Pr0zav]

I know this is pretty late....

Try downloading smc fan control, it controls the fans using software. You can see all the info about fan speed and system temps in dashboard when its running.

Just set your fans to be at about 2000 rpm's or higher/lower depending on what you are doing or the noise level you can tolerate.

Maybe your temp sensors are screwing up and making the fans speed up.... you will be able to see if this is the case in smc fan control as it gives you the readings of the temps too.

SMC should help stop the fans from taking off whenever they want..... but remember, DONT turn you fans rpm's too low. The heat build up may damage something because the normal software wont kick in and make them speed up.. you will need to keep an eye on things because with smc you will be in control of the fans... 2000rpm or slightly more should be good for cooling and still be quiet too.

EDIT- Actually its iStat that will give you the dashboard reading of temps etc... get that widget, so to keep an eye on temps when smc fan control is running

One of the most common causes for speeding fans on iMac's is heat sink sensors that for some reason or another started to act up, it could be that they have come lose. If you are comfortable with it then open the thing up (if not under warranty) and check the sensors, if under warranty call apple and they'll sort it out for ya.

[mrwichtig]

the newest iMac have stored the temperature sensor inside the harddisc.

Do you change your harddrive on your mac?

(google: cBreeze)

[kwekuboateng]

install cleanmymac. it will help or find mackeeper. that will free some system files that are not been used.

[havocn16]

this is a problem they have on all I-macs really annoying.