Chosen Solution
How is the cooling configured inside the 2017 27" iMac? Is there a heat-sink on the GPU? Is there space to attach one if there is not? Are there any potential options to improve the cooling for any of the core components (i.e; replace thermal compounds with higher performing ones, attach heat-dissipation to GPU/CPU that currently lack any)? Thanks!
Lets try this, Install this app: TG Pro it will allow you to see the internal thermal sensors and whats happening with the fan. Once you have it running take a snapshot of the main window when its at a point you are getting concerned of the running temp and paste it here for us to see Adding images to an existing question. As far as your direct question your system has two heat sinks one for the CPU and a second of the GPU. Both feed the heat to a fin system for the fan to extract the heat and push it out through the back of the system. I would leave the cooling system alone as it as its quite good, unless you have something show up under TG Pro. Then we can see what actions would be needed then. The simple steps is to make sure the vents along the bottom and back are not blocked so the system can breathe. Also make sure you’ve not over taxed the system running processes which are over stressing it.
I think ’thermal throttling’ occures when the GPU reaches 80°C resulting in lower fps (i did quite some testing now). I would like to improve the cooling capabilities as well and thought of this: The foot/stance of the imac is an external heat sink of some kind. The exhaust is venting the hot air directly onto it. Maybe one could add a fin/heat dissipation thingy with thermal glue to it. Right above the hole for the power cable. Then use a quiet fan. Not sure hot to measure the success though. I guess a GPU temperature of 77° C with 300 less RPM on the main fan would be an improvement. It’d go from “noisy as !&&*” to “I can live with it”.
