iMac GPU Overheating (Late 2014 build)

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Level 1

4 points

iMac GPU Overheating (Late 2014 build)

Hello Everyone!

I was doing some searching around on this forum and found that apparently this is a common issue. I know Mac's run hot, but I think mine is getting to the point where it completely shuts down.

While surfing the web or doing any generally low taxing activities on my computer, the system runs fine. The fan never speeds up, everything is normal.

However, any time I start up a game (I know Mac's are not for gaming), I'll usually get 10-20 mins of play time and then start to notice performance issues. I have a frame rate counter on while playing and it stays fairly consistent with no drops on the counter, but the game will start lagging. Like while playing driving games, it's like the vehicle surges while driving. Going normal speed, then slows, then normal speed, then slows. Even though the frame rate stays consistent. Doesn't make the game unplayable. Just annoying. Even when I change the graphics settings to bare minimum to try and make it easier on my computer, the surging still happens.

It's even worse when I try and run the same game on Windows using Bootcamp. I'll get 10-20 mins in, sometimes less, and the whole computer will shut down. Not restart. Just flat out shuts off. I have to start it back up using the power button on the back of the computer. No errors. No blue screen. Nothing. Even checking Window Event Recorder program does not point any fingers. Same thing with the graphics settings. Will lower everything to bare minimum and the computer will still shut off.

I downloaded a fan speed controller app, I forget which one, and noticed that my GPU temp was sitting at 80 C. Mind you this was while the computer was at rest. I wasn't running anything. All of the other temps (CPU, hard drive, etc.) were cooler. Some were 70's. Some were less. I set the fan to full blast (2800 rpms) and was able to play for a little while longer, but the computer still shut off after a period of time.

So, my question is, if the Windows operating system notices the GPU hit a certain temperature, would the entire computer just shut down? It only completely shuts down while using Windows. I only notice performance issues using MacOS. The computer does not shut down while gaming on the MacOS side.

Computer Specs:

27" iMac 5k Retina (Late 2014)

4.0 GHz Intel i7

8 GB of RAM (I think. I'm currently not at home so I am not positive on this)

1 TB Fusion Drive

4 GB AMD Radeon R9 M295X

iMac Line (2012 and Later)

Posted on Aug 10, 2022 10:41 AM

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Answer 1

Top-ranking reply

Mal-S

Level 5

4,984 points

Aug 11, 2022 2:03 PM in response to b154wheel

Try resetting the SMC.

Reset the SMC of your Mac - Apple Support

Another option is to buy a small standalone USB fan and position it to blow on the part of the computer hottest to the touch.

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Answer 2

b154wheel Author

Level 1

4 points

Aug 10, 2022 6:20 PM in response to b154wheel

So, I inspected the air vents at the bottom of my computer and they were basically completely clogged with dust and junk. Using a can of air, I blew all the junk out and opened up all the vents.

Turned my computer on and let it sit there for an hour or so idle and the GPU was around 70 C. Seems to be an improvement. Started a game and let it sit at the title screen. After about an hour, I took the picture below. Everything looks great, except for the GPU temp. I think 105 C is still within the limits, but I don't understand why that and only that is so much higher than everything else. No shutdowns yet though.

Is there a separate heat sink for the GPU? It might be covered with junk or the thermal paste may be no good anymore.

I am going to test some more by actually playing the game and see if it shuts down the computer.

I'm afraid I may have to open my computer after all.

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Answer 3

b154wheel Author

Level 1

4 points

Aug 11, 2022 8:43 AM in response to b154wheel

So, after sitting at the game's title screen for about an hour and the GPU temp being above 100 degrees C with the cooling fan on full blast, I decided to start playing the game and see what happens. I was able to play normally. However, the performance was not perfect. Game was playable, but the vehicles while driving were surging. Basically the same issue while playing the game on MacOS. But, I was able to play the game for a bit. I saved my progress and closed the program to adjust my sound and double check the temps again on my fan controller app. Everything seemed fine. GPU temp was down a bit. I think it was in the 80's. I restarted the game and was able to play for like 5 minutes before the computer shut down again. I think I'm going to have to open up the computer and take a look inside. I'll keep updating as I figure this out.

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Answer 4

Johnb-one

Level 6

9,180 points

Aug 11, 2022 8:56 AM in response to b154wheel

Hi, b145wheel, you've basically done all that Apple recommends you do...keeping the external vents free of dust, fuzz, hair and junk, and ensuring a good airflow.you could try using a DataVac which is a special antistatic vaccum designed for Computers. on the outside vents. you have cleaned off the dust, fuzz, hair and junk off of the bottom of your iMac, above the foot which would be the incoming vents ...perhaps there are outgoing vents that need to be de-dusted, de-fuzzed, de-haired and de-junked...other than using a box fan behind the imac, say, in a window, to keep the air moving, I'm out of ideas.... opening your iMac is completely on YOU, and Apple doesn't condone, encourage or support us Mac users doing that at ALL. so there is nothing more I can say or discuss with you here.... at least not in an Official Apple Forum....you may find forums and info elsewhere to help you out, but not HERE..... on a side note, iFixit has an interesting line of products that you might want to have a look at....I'll say no more

John B

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iMac GPU Overheating (Late 2014 build)

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