Late 2015 iMac - Motherboard replacement

[dubmick]

Hi

My iMac has been overheating and shutting down over the last 6 months. I brought it in to an authorised repaired and their initial assessment is that is need a new motherboard at a cost of €719. Anyone have experience with an issue like this? I have it just over 4 years. Apple as expected won’t cover.

It’s my second iMac and it could be my last if they barely last 4 years.

 

[TwoH]

Well it is fair to assume there's a fault with the logicboard in some capacity.

I have seen these models with issues - are you sure this is an overheating issue? What temperatures are you getting on a stress test when the machine is shutting down?

Could be a different intermittent fault such as RAM, or HDD.

 

[dubmick]

Not sure about temps but it seems to shut down when the fan is running at top speed for a while. Very little seems to get the fan running. 4K YouTube video and couple of other apps usually does it.

 

[CooperBox]

It's 5 years old and depending on your working environement the fans may be completely blocked, and/or the CPU/GPU thermal paste could have been poorly applied and now serving no useful purpose. I suggest you don't spend a cent on it until you at least check the fans and their exit areas for blockage.
I was horrified at the build-up & clogging of dust & debris in all 3 fans of my mid-2010 iMac, and removed them completely for efficient cleaning at the same time as an SSD upgrade.

 

[killerrobot]

One of your fans might be shot. I had a 2008?? iMac where the HDD fan?? was shot but the others were working fine. Took me forever to troubleshoot it as I could here fans running (loudly at that) but then replaced the fan for 30 dollars with an ifixit kit.

Run a hardware test and see if there's any codes for failing hardware.