MP 1,1-5,1 What is safe PSU temps cmp5,1


macrumors 68000
Original poster
Dec 12, 2005
Hay in the UK & we have a small heat wave, iv seen my PSU sensor 2 hit 67c+ at default settings.
After that iv set the PSU fan to keep the PSU sensor 2 under 50c but at 1400-2000RPM it’s a real pain.
2000RPM and still 49c on PSU sensor 2 !

So is it safe to let it get that hot?
Anything I can do to help keep it cool?

been around 28-32c ambient :eek: normal temperature is closer to 16c, im just not used to the heat it's killing me.


macrumors regular
Jul 30, 2018
Give it a good cleaning with some compressed air, pretty sure that's the problem.

30°C ambient, Mac Pro very near the back wall and PSU2 temp at 41°C with fan spinning at 600rpm


macrumors G5
Apr 3, 2014
Hong Kong
There are at least two different models of 5,1 PSU. AFAIK, the Delta one is noticeably cooler.

I can easily keep my Delta PSU at around 40°C most of the time with the PSU fan a bit above idle RPM (system ambient 35°C.

This is my PSU fan RPM record in the last 30 days.
Screenshot 2019-07-27 at 9.28.32 AM.png

And this is the PSU (2) temperature.
Screenshot 2019-07-27 at 9.28.39 AM.png

I sold another cMP with the other PSU. That run significantly warmer. From memory, even with higher fan speed, the PSU can barely stay at 55°C.

Anyway, this post has some discussion about PSU temperature.

Even no conclusion what's the safe temperature, but worth to have a look.
[doublepost=1564191709][/doublepost]Also, what I found is that the PSU 2 temperature (AKA "PSU component" temperature in some software) will be ~5°C warmer if I move the super drive from upper slot to lower slot.

I moved my super drive to the lower slot due to the sticky upper super drive door (on the case side), and found the PSU temperature is affected.


macrumors 68000
Original poster
Dec 12, 2005
I now have ‘fixed’ it by using a laptop for all light things which works for the heat wave.
I gess i have the AcBel PSU

The dvd bay is empty just two SSD’s and i have taped open the DVD doors to let more air in. with ambient temps of 28-32c it just runs hot, assume it’s a mix of age and lower quality PSU so maybe no real solution.
As a plus as soon as there’s about a 200w+ load on the system the PSU drops by about 10c and the fans slow down to only 1200-1400.
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