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macrumors 65816
Original poster
Feb 4, 2007
Just noticed that the fan runs loud and constantly when I open a browser like firefox or safari. So I installed macs fan control. See attached.

The PCI and PS(Not sure what PS is.?) seems to be running high for some reason and then slows down. I have OSX sierra. The main OSX is on a pcie ssd.

The graphics card is an amd 7950 and is the only graphics installed. See attached image of what I see in the system report.

The fans are quite now but they do run high when you open browser or some small app. not sure if i have to be concerned.




macrumors 6502a
Jan 28, 2016
Belgrade, Serbia
@Filin I think that is the case with nVidia GPUs only.
I've had 3 HD79xx cards (two 7950 and one R9 280X I still own) and never had similar issue.
PCI and PS fans are ramping in my Mac when GPU is under load and hot, but 25˚C for PCIE Ambient is far from hot.
Screen Shot 2017-02-20 at 9.11.39 PM.png

You can see my PCIE Ambient with two monitors connected. When I connect only one, it goes down to 30-32˚C and PCI Fan goes back to 800RPM.

@cpnotebook80 , Im almost positive that rivet has snapped on your Northbridge heatsink.
But I don't think that is causing any problems you have.

Yo-Yo Buffalo

macrumors newbie
Dec 6, 2017
Weird, my Mac Pro 5,1 fans have just started going nuts too. They are always on and often at full and very loud. It always used to be silent unless i was doing heavy work.

I can't figure out what it is. Nothing has changed, I've not upgraded or installed anything.
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