brand new 5k imac GPU heating to ridiculously hot levels under mild use

1. I believe there is a single fan in the latest models. Does it speed up when this is happening? 2. If you sleep the Mac for an extended period of time, does the GPU cool down, or is it showing the same, or close to the same, temp? 3. I would run the hardware test to see if it's maybe a faulty sensor giving you an inaccurate readout of the GPU. 4. What temperature/fan program are you using?

http://support.apple.com/kb/ht1509

contact apple support by phone and mention heat.

You still have your Apple Care 90 days and 1 yrs. warrantee that free without purchasing the 3 yr. extended plan. Give them ( Apple Care Support ) a call. # is in your contacts. Best to get a case # going with a new machine. Sounds like you're covered. It's a new machine and your on file with them. They will answer your questions and make a case #. And they call back to see how you are doing.

Hi

Here i use an app that uses 25% CPU & GPU (probably 100%) but....

In default for my OSX Yosemite, fan-controlls my GPU-die up to 100-105´C but with FAN-controll 3party app i put my fan on steady 2150rpm, then its "normal" 92´C for my GPU die... or is the GPU-die normal on 100´C ??? because rest of the GPU meters says 44´C and thats like normal... but the GPU-Die as you can se in picture is 92´C.

Hope Apple release at firmware to GPU, and "Clock down a little" to fix the heat problem in new iMac 5K, Late 2014 computer, or... drivers update to AMD Radeon R9 M295X, to fix this... annoying problem.

//Johan Norberg

Sweden

And why does "GPU Core Low Side, show..... 56.70A !!!?

Have the similar situation with my new iMac @ R9 M295X.

While playing games (Warcraft, for example) «GPU Die» sensor grows up to 100 C and falls back to normal (50-60 C) within half a minute after i quit the game. No glitches, artifacts or shutdowns/restarts, but the digits are scaring me.

What is «GPU Die» sensor anyway? What's the difference between it and «GPU Proximity»?

Is it safe to play on my iMac with these temperatures?

Almost going to purchase a unit, in these case better wait & see!

Well i have played Mafia2 in highest resolution in game without problem (-2x Antialiasing, and lower on shadows and so on..) and the game goes smooth. Yes sometimes the GPU does speed up the fan, but... for me its OK performance in total of the game.

But still i am a little bit worried about the GPU-die thats near 100-105´C, i think normal for hardware is about 90-95´C when it works 100% but... 100-105´C a little bit scary.

So i hope someone in thread can explain or Apple the differens between GPU-die and GPU-proximity, and also why GPU-core-low-side is showing about 57A (i think A stands for Ampere), and if its... "57A" then...or maybe my 3rd part app "i-Stat Menus" is showing the wrong A on "GPU-core-low-side" information.

GPU proximity is just that. The sensor is near the GPU, not directly in it. Same with any of the other "proximity" sensors. From my Late '09, missing even a GPU proximity sensor. Relatively recent version of iStat Menus, which includes all these "proximity" ones. Don't know what to make of the very high readouts for the GPU Die in your models. Temperature Monitor (free) no longer being supported, but maybe Marcel Bresink, in Hardware Monitor (paid--if it's still being supported for new models) has a note about those. Since those temps are showing high for everyone here, I'd be inclined not to worry about them and use the GPU Proximity as a more reliable guide as to what's going on.

And then from Hardware Monitor, which shows all the same sensors, but with different names. For example, Power Board Proximity is called Power Supply Position 2.

In mine the Northbridge makes a decent proxy for the GPU.

I have a new iMac 5K with the R9 M295 under normal browsing my Fan is about 1220 and the GPU Die is 52C. As soon as I start a YouTube video in theatre mode it moves up to 60-65C. If I do full screen it moves up to 70-75C. Fan speed remains around 1200. The ambient room temp is 67F.

I will check the other new one I have to see if it is the same.

Update to my earlier message.....

I have a second iMac 5K with R9 M295 graphics and just after sleep it has a fan speed of about 1200 and Gpu Die of 65C for full screen Youtube video. A little cooler I guess since it had just woke up. It also only has 16G ram vs 32 for the above Mac. Not sure this affects much but this Mac does have a resolution setting scaled one setting bigger that the Retina optimum.

You are entitled to 90 day telephone support from Apple. Try contacting them.

Apple Support contact - Telephone

You don't actually know what's recommended and what's not. You're going on guesses based on 3rd party users?

I'd say... quit monitoring temperatures. If you get machine problems down the line contact AppleCare.

UPDATED:

After watching a full screen Youtube video for about 10 mins it hit 92C and sensor turned red. I opened a case with Apple and for now they have no safe max temp. And as long as the fans are running low and the system is performing fine then there is no action needed. But case is on file.

Previous Post:

I have a new iMac 5K with the R9 M295 under normal browsing my Fan is about 1220 and the GPU Die is 52C. As soon as I start a YouTube video in theatre mode it moves up to 60-65C. If I do full screen it moves up to 70-75C. Fan speed remains around 1200. The ambient room temp is 67F.

I will check the other new one I have to see if it is the same.

I just Got my 5K maxed out iMac (4GB GPU and i7).

idle it sits around 60c for GPU and CPU , but do anything with video or use handbrake and it goes to 99c for CPU, or play games and GPU is over 87C.

I guess apple care will cover it for 3 years, but really what the long term longevity of such a machine running at these temps for long periods ?

My thoughts it really should have a liquid cooling system, I guess the next model?