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2008 Mac Pro overheating problem / screen freezing but can still use mouse

Hi there, 


So I've come across a problem that I can't seem to pinpoint on my 2008 Mac Pro/10.11.6/16GB. It initially started with the screen freezing, but the mouse would still move and audio would still be going. This would happen every day or so to start, then getting more frequent, and I'd have to manually restart with the power button each time. I've come across this problem in the past, and I’m guessing the GPU was overheating. What initially solved the problem for me was actually cleaning the dust off of the RAM/heatsinks in the compartment below the GPU, as it seemed those had gotten gunked up over the years, and were running super hot and the heat rose to the GPU right above. After I cleaned the dust out it worked for a couple years, but now the problem’s happening again. So I removed the dust off the GPU and RAM, and also the dust behind the CPU+RAM fan, as well as the dust in the superdrive compartment and the power supply. No dice. I've also reset PRAM and SMC, booted in safe mode and running disk utility on the HD, and run a hardware diagnostic test, to no avail. There’s 220GB free on my hard drive, so not low. 


In the process I discovered (via iStat and Macs Fan Control) that not only was the RAM and GPU getting hot, but so was the power supply. Right now the computer doing nothing intensive, and the RAM riser A slots are 80°C/74°C, and my PSU is 68°C/61°C. I’ve seen other people’s sensor readings saying that their power supply is 45° or 55° max. Is it possible that the power supply is sending out too much juice and causing other components to overheat? Or maybe my sensors are misreading? The graphics card and RAM are all really hot to the touch. Another curious thing that has me perplexed is that despite these hot readings, the computer’s fans are all running at the minimum. You’d think they’d be cranking up to cool down these hot temperatures, or is it something else which determines the fan speeds (like CPU load)? Anybody have any ideas? I know my computer is old, and pushing for Methuselah-status in computer years, but it still works fine for me and I’d love to figure out what’s going on and fix it.


Thanks.


Mac Pro, OS X 10.11

Posted on Mar 1, 2022 10:25 PM

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Posted on Mar 2, 2022 8:40 AM

Reports of systemic problems caused by power supply overheating are extremely rare. These assemblies are designed by Analog engineers who know the parts they are specifying. The typical problem of a Power Supply is complete failure to turn on.


Your other guess (of graphics card issues) is more likely.


Caution: do not replace the graphics acrd with the same graphics card. UPGRADE, don't replace. A more modern graphics card can compute faster and run cooler.



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Question marked as Top-ranking reply

Mar 2, 2022 8:40 AM in response to relicpro

Reports of systemic problems caused by power supply overheating are extremely rare. These assemblies are designed by Analog engineers who know the parts they are specifying. The typical problem of a Power Supply is complete failure to turn on.


Your other guess (of graphics card issues) is more likely.


Caution: do not replace the graphics acrd with the same graphics card. UPGRADE, don't replace. A more modern graphics card can compute faster and run cooler.



Mar 2, 2022 7:27 AM in response to Grant Bennet-Alder

Yeah, still the original graphics card. I was about to replace it a couple years ago when this was happening, but after cleaning the dust from the RAM it started working fine again, so I figured what was going on with it was a symptom of the problem and not the root of the problem itself. I just don't want to replace it and then have the same thing happen with a new one, if the problem is elsewhere. If a power supply is hot/overactive, can it cause other parts of the computer to overheat?

Mar 2, 2022 8:59 AM in response to relicpro

The temperatures you reported are NOT alarmingly hot. Your Mac is expected to run all day every day at 60 degrees C without any issues.


if it gets hotter, the fans will spin more intensely to dissipate the heat. The fans fail-safe at MAXIMUM speed.


if it approaches 100 degrees C, it will do an emergency power-down to save itself from heat damage.

Mar 2, 2022 9:05 AM in response to Grant Bennet-Alder

Okay, good to know they're not exceedingly hot. And the odd thing I mentioned above is that despite the sensors reading hotter than "average" temperatures, the fans are still running on minimum speed, and the computer isn't even trying to cool itself down. Oh well. I suppose these old boxes are bound to have some idiosyncrasies.


I'll try another card.

2008 Mac Pro overheating problem / screen freezing but can still use mouse

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