Issues with iMac cooling

If MFC & increasing fan speeds doesn't help, have you blown the dust out lately, or you may need to replace the thermal Paste on CPU, GPU.

dialabrain wrote:

I never saw the post, however, I have three iMacs here along with an iMac Pro and it's not remotely possible to tilt the screen far enough to block the vent. Maybe if the hinge was broken.

Good morning,

The tipping does not have to seal the vent, the stand's neck needs only to be close enough to disturb the airflow. When helping the OP I mentioned whose tipped-down case was causing overheating, my 2017 was new and running cool. When I duplicated here what the other poster described as his screen position, the temp monitor software on mine started climbing. When I returned the monitor to the "beauty shot" position Apple uses in adverts, the temps returned to normal.

OP's temps went down when he "un-tipped" his, and I was able to reproduce at will temp increases with the same model iMac by tipping the case forward. In neither case did the stand need to touch the vent.

This was very common with desktops Macs in the pre-intel days. Form factors like the Beige G3 desktop, the 7600, and other "box"case" models all exhausted air straight out the back, and they would start to heat up if there were less than 4-6 inches of clearance behind.

The other thread would have been late 2018 or early 2019. I got this iMac in late Oct 2018 so it had to be after that. I have poor results search for old posts.

Before I would try an ice bag I would look at Macs Fan Control.

Not much you can do, a big Fan blowing on the back or from the side to cool it a bit more I guess.

Allan Jones wrote:

One thing to check that showed up here in an overheating post about 18 months ago: If you have the computer placed above sight line so the screen is tipped down, the iMac's stand blocks the important exhaust vent.

I never saw the post, however, I have three iMacs here along with an iMac Pro and it's not remotely possible to tilt the screen far enough to block the vent. Maybe if the hinge was broken.

Well, because I'm a glutton for punishment, I installed Fanny and tested my 5K iMac for an hour tilted all the way back, forward and vertical. As I suspected there was no difference in avg temps. Maybe my iMac is broken. :)

I wish I would have thought of that. lol

I didn't see your post when I first click on the reply button.

OK, great news that I could help in some way, take care my friend. :)

+1

With MacFanControl you can monitor the iMac's temperature sensors and control the cooling fan rpm.

https://crystalidea.com/macs-fan-control

With MacFanControl, you have the option to manually run the fan at a higher rpm or to automatically increase the fan rpm based on the temperature of the CPU.