iMac CPU fan periodically runs at max speed.
Hello amazing people! :)
I've got this great iMac 27 inch that troubles me.
Model: MB953 / A1312 / EMC 2374
Issue: CPU fan is running at MAX speed. Sometimes for a few seconds, a minute and sometimes until I power it down.
When: Whenever it likes. It doesn't matter wether I'm running Final Cut, rendering HD movies, browsing the web for funny cats or if it's idle in standby mode.
Safe to say, it's incredible annoying.
I've got this monitor program, and here's what it tells me, when my iMac er running normally.
CPU heat: 38 degress (celcius)
CPU fan: 1500ish RPM.
Now, when the issue happens, the readings are:
CPU Heat: 38 degrees (still celcius)
CPU fan: 0 RPM (<-- what!?)
Yes, 0 RPM is making enough noise to wake up my entire building (Or at least me...)
What is wrong with my iMac?
My own logic sense, would say; There's something wrong with the CPU RPM reader, making the system to believe, that it's actually running at 0 RPM. Therefor opening up everything to blast air trough. Might also be the heat reader? But my CPU heat reader seem to work fine. (Various temperature readings)
Note: It's ONLY the CPU fan. HDD and ODD fan functions as intended.
So, as suspected, my iMac would make some noise again.
The iMac was idle/standby mode, when it happen. Proximately 15-20 mins. after I last used it.
The fan went to "slow" speed after 5 mins.
Here are the readings from TG Pro and iStat.
TG: 1520 RPM
iStat: 0 RPM
The noise is a lot louder than this. (Probably max speed)
Is this a good question?