2015 5k iMac high GPU diode temps

[coatsy69]

Recently I have been having issues with my mid 2015 5k iMac of having the fan come on alot more than it had in the past. Since I bought it, the fan has almost never come on. From photo and light video editing, to even some low level gaming, I never heard the fan kick on almost ever. Now I can't even watch a youtube video in 720p without the fan ramping up into the 2000's. Its a 3.3GHz i5 with an M290 and 8 gbs of ram. I downloaded the fan control app to keep an eye on temps and noticed the only thing that gets even remotely hot is the GPU diode temp. All the rest of the CPU and GPU components are barely even at 150 degrees, while when im watching a video only the GPU diode ramps up to about 185, kicking on the fan into almost the 2k range and it stabilizes there until I pause the video or go to another web page, at which page the fan will shut down almost immediately and the temp will drop down into the 160's. It will even spike the diode temp with just a single .gif on a webpage... Its getting a little ridiculous at this point. Its worth noting I do have an external 4k LG monitor hooked up, but this has happened months after adding that to my setup. Any ideas? I've reset the SMC and that did not help and the Mac is clean of any dust and vents well. Not sure what to do

 

[casperes1996]

PS: When talking about hardware temperatures, generally Celcius is used.

I have the R9 M295X, and let me tell you, mate. You haven't seen hot yet. My GPU diode temp is typically at 105°C (221F). The fan speed needs to go to 3600RPM to keep it from overheating, at 110°C(230F) at which point the Mac automatically goes to sleep to prevent component damage. Which has happened... More than just a few times.

Dust accumulates over time, more software uses GPU acceleration, new video codecs come along, etc.