iMac Internal Temperature Concerns

[1tomcat1]

I have a 2011 iMac A1312, 12,2 27 inch LCD running El Capitan without any obvious operational issues.

I am aware that this model has a long history of overheating issues. I have the AMD Radeon HD 6970M, 1GB video card which I have been monitoring with Macs Fan Control software. All hardware temps are normal except the GPU diode which idles at 50 degrees C, and 60 degrees C when doing normal internet surfing....and as high as 70 degrees C when streaming video. The 70 degree C reading concerns me, it appears to be too hot.

So I may need some help here, assuming there is a problem....

First ,I will look inside the machine and clean out the dust and dirt from the vents, fans and heatsinks. I will then button it back up and see if the cleaning process improved the temps....if so, that may be the end of it! If not, I will be asking for more input on how I should proceed.

My gut feeling is the high temps are the result of the thermal paste breakdown on the video card since the machine is 6 years old. At this point... there are no screen issues or artifacts. I am thinking seriously about removing the logic board and video card from the case and installing new thermal paste on the video card and the CPU. I am confident that I can do this even with all the connectors on the front and back of the board. Does this make sense or am I making a problem where it doesn't exist?

Anyone have any comments or suggestions at this point?

 

[casperes1996]

I am aware that this model has a long history of overheating issues. I have the AMD Radeon HD 6970M, 1GB video card which I have been monitoring with Macs Fan Control software. All hardware temps are normal except the GPU diode which idles at 50 degrees C, and 60 degrees C when doing normal internet surfing....and as high as 70 degrees C when streaming video. The 70 degree C reading concerns me, it appears to be too hot.

My GPU goes to 105C°... 70 really isn't that high for a graphics card. Now, the real problem with these chips isn't the overheating in and of itself, as they actually stay within rated temperatures. If you run them hot constantly there are not an increased likelihood of problematic behaviour. The problem really starts surfacing when you have a lot of temperature shifting, so going hot then cold then hot again a lot.
Eventually it's almost inevitable your GPU will die, but I wish you the best of luck in keeping it alive for as long as possible. Mine lasted three years in my 2011 MacBook Pro. Roughly anyway.

 

[nambuccaheadsau]

You may well be better disabling any fan control software and see if your iMac handles the problem, which is in no way severe. If you replaced a hard drive it may be time to consider a heat sensor kit from OWC.

 

[1tomcat1]

nambuccaheadsau: the fan software was installed to only monitor temps....I didn't set it up to control anything. The hard drive it came with, is a full-sized, 2T WDC WD20PURX-64P6ZY0, 5400 RPM. The drive fails the AHT, but there is no racing of the fans which indicates some type of sensor control is likely present. I will check the drive connection when I open up the machine to clean it. I do have new OWC sensor cable if I need it. Since the drive is made for AV use I will probably replace it with a new 2T mechanical storage drive and add the OWC drive kit and install a SSD for the OS under the optical drive.

 

[nambuccaheadsau]

Sorry to disagree, but all 2010 and 2011 iMacs came with a 7200RPM, or an SSD if ordered with one. The next model, 21.5" 2012, came with the 5400rpm HDD and this does not require a heat sink sensor cable at all, but the 27" does.

 

[1tomcat1]

No disagreement here nambuccaheadsau....I just stated what drive the machine had in it when acquired from a online bidding site. The original shipped drive or SSD had obviously been replaced with the WD unit by the original owner.

 

[cynics]

I don't feel those temps are that absurd, at least not for an iMac. Where are you streaming videos from that you see temps that high?

It wont hurt to clean the dust out of it. Hard to say whether its a problem without looking. I would use a very high quality thermal paste if you decide to reapply it since its unlikely you'll see a difference otherwise. I recommend Grizzly Kryonaut or Gelid GC Extreme.

 

[1tomcat1]

cynics:most of the video i stream is from youtube....mainly Nashville based music groups like the Time Jumpers and Music City Live sites....

 

[cynics]

cynics:most of the video i stream is from youtube....mainly Nashville based music groups like the Time Jumpers and Music City Live sites....

Its tough to say if it will help cleaning it out and reapplying thermal paste will help because the depending on the fan profile it could just wait longer for the fan to rev up and/or not speed them up as much. So it could operate at the same temps but at lower fan rpms.

For example I just upgraded the CPU in a laptop I have and I ran my own benchmark (timed a video encode in handbrake) to see the difference in performance. However while I was at it I recorded temps since I had to reapply the thermal paste. Both CPU's have the same 35w TDP.

Before

After

Only relevant information there is the fan rpm max and CPU 0 and 1 temp max. So fan RPM and temps dropped significantly.

However while watching a youtube video the temps are about the same, except the fan is spinning slower. Its depends on the Macs fan profile what the temp is going to do.

 

[1tomcat1]

Update: finished cleaning and upgrading the 2011 27 inch A1312 iMac. The unit was pretty fuzzed up inside especially the fans. It was last opened up/serviced in 2014 which was written on sticker inside the case. It cleaned up well using a can of air and a camel hair brush. I removed the internal boards including the logic board and cleaned and install new compound on CPU/heatsink. Also cleaned and installed new pads and compound of video card/heatsink. I replaced the existing 3.5 inch, 5400 RPM, hard drive with a new Samsung SSD and the OCW temperature sensor cable. I put the machine back together and it booted up fine. I let it run for a few hours then did a little video streaming. The video card temperatures remain almost the same as before, but most noticeable is the fans seem to not be running as fast as before. I suspect this is due to the OCW sensor cable installation and the internal cleaning especially the fans. Frankly, the machine just seems to not have to work as hard cooling the hardware now. Oh while I had the machine apart, I did install the OCW SSD cabling from the logic board and routed it under the optical drive....I didn't install a drive but may use it in the future for a internal storage drive.

Originally, I didn't think the machine had the racing fan syndrome, but now with the upgrades process complete, it's obvious that it was a issue.

Removing the iMac internal components wasn't hard following online videos.....but I did take a lot of pictures of the front and back of the boards before I removed any cables. There are a lot of cables, so the pictures really came in handy to make sure it went back together again without any problems.
[doublepost=1492878765][/doublepost]Update 2: the machine seemed to boot slow.... forgot to select the SSD as startup drive...DUH! Also enabled the trim function without any issues. The machine now boots up in about 30 seconds....pretty impressive compared to the old platter hard drive.

 

[1tomcat1]

Update 3: new symptom has suddenly appeared...periodically the LCD goes black and the machine reboots! This has happened three times in about a hour. The only thing I have done since it started acting up is I messed with the Mac Fan Control Software settings. I restored the software to the original settings but still got another reboot afterwards. If it happens again, I will remove the software and see what happens.....
[doublepost=1492887947][/doublepost]Update 4: rebooted again, so I have removed the fan control software.....time will tell if this was the problem!

 

[1tomcat1]

It's been running flawlessly for about 7 hours, no further black screens or rebooting....must have been a software conflict or glitch