Resolved iMac fan 0rpm

[gian8989]

I use iStat Menus 6 and TG Pro to monitor the fan. I notice that sometime the fan won't run after the iMac goes to sleep. First of all as soon as I change from auto to manual control and to auto again the fan start spinning again. TG Pro has an option to disable fan control when mac is sleeping: could this be the problem?

I was wondering if someone else had this problem.

 

[colodane]

The fan does indeed turn off at times during sleep. This isn't a problem, but rather a feature. If you look at the iStat data during sleep (retroactively) you will see that the loads on some of the power rails are shut down and, of course, the power dissipation goes down. When there is not a need for cooling, the fan will turn off by design.

On my particular machine, the only two fan speeds I've seen are about 1200 rpm during operation (I don't tax the machine heavily) and some periods of 0 rpm during the nighttime sleep setting. I'm happy with that.

 

[gian8989]

The fan does indeed turn off at times during sleep. This isn't a problem, but rather a feature. If you look at the iStat data during sleep (retroactively) you will see that the loads on some of the power rails are shut down and, of course, the power dissipation goes down. When there is not a need for cooling, the fan will turn off by design.

On my particular machine, the only two fan speeds I've seen are about 1200 rpm during operation (I don't tax the machine heavily) and some periods of 0 rpm during the nighttime sleep setting. I'm happy with that.

The problem is not that it goes to 0rpm during sleep but that it doesn't spin again after wake up.
Yesterday I noticed after 10 minutes that it was still at 0rpm and CPU was at 74ºC.

 

[colodane]

The problem is not that it goes to 0rpm during sleep but that it doesn't spin again after wake up.
Yesterday I noticed after 10 minutes that it was still at 0rpm and CPU was at 74ºC.

I see. Sorry I didn't understand your first post.

I agree that 10 minutes at 74 degrees C seems like it deserves some cooling. Not privy to Apple's algorithms for heat management of course, but that intuitively doesn't seem right.

Unfortunately I can't be of much help as I've never seen CPU temps anywhere near that. 60 degrees is rare here, and the CPU cores typically are around 40 degrees C during normal operation. The fan is only off during sleep when the CPU temps are below about 30 degrees.

Is your iMac operating correctly during all of this? What does iStat report for "Total Power" in watts during sleep and normal operation?

I'm not at all familiar with TG Fan Control. Perhaps your suspicion about its behavior is valid. I've used only iStat menus here (both version 5 and now the new version 6) ever since I bought this Mac and have not have any issues with cooling. I've never tried to manually control the fan.

 

[gian8989]

I see. Sorry I didn't understand your first post.

I agree that 10 minutes at 74 degrees C seems like it deserves some cooling. Not privy to Apple's algorithms for heat management of course, but that intuitively doesn't seem right.

Unfortunately I can't be of much help as I've never seen CPU temps anywhere near that. 60 degrees is rare here, and the CPU cores typically are around 40 degrees C during normal operation. The fan is only off during sleep when the CPU temps are below about 30 degrees.

Is your iMac operating correctly during all of this? What does iStat report for "Total Power" in watts during sleep and normal operation?

I'm not at all familiar with TG Fan Control. Perhaps your suspicion about its behavior is valid. I've used only iStat menus here (both version 5 and now the new version 6) ever since I bought this Mac and have not have any issues with cooling. I've never tried to manually control the fan.

I also have istats menu but i am pretty sure that this is a problem of TG Pro since i never used istats to control fan. I have to ask them if the option to "ovveride system control" require to set a rule to make the fan always spin at basic rpm or if it is a bug.

 

[adnbek]

Try resetting th SMC and see if that fixes it