Mac mini late 2012 heatsink

[peterjcollins]

Hello all,

I own a Mac mini late 2012 model, the i5 model. It is running under Catalina at the moment, and I have to say that with 8GB RAM it is very smooth and responsive, so I'm happy with it. Last week I did a bit of maintenance, I added a second HDD to the SSD that was previously installed into the machine, and, while I was there, I decided to clean the cooling system, and to replace the thermal paste. I used Arctic MX-2, and when reassembling, I noticed that the heatsink correctly touched the CPU, while it was not touching the Platform Controller Hub chip. The screws are correctly threaded into the right holes, with springs. It is very strange. I just added a little bit of thermal paste, so the chip is now touching the heatsink through the paste itself, but it is very strange indeed. I found some kind of old post on the Internet dealing about the exact same thing, but I was curious to know if you experienced something similar. The mini works perfectly after the maintenance. I did some tests and while running 10-minute Cinebench R23 benchmark test, the CPU reaches 83°C, with fans at minimum speed (1800rpm). My other mini (exact same model, but with High Sierra 10.13.6 and original thermal paste) doing the same reaches 78°C. The Platform Controller Hub chip reaches 66°C, while on the other original High Sierra mini with original thermal paste) reaches 64°C. Maybe it's only because one runs High Sierra and the other runs Catalina, but I was wondering what do you think about it.
Have a nice weekend!
Lorenzo

 

[Miat]

IIRC, the PCH chip isn't meant to be heatsinked. Pretty sure there is already a thread on it here somewhere.

 

[peterjcollins]

Thank you for your answer.
I looked around the forum and I actually found something, but as far as I can see, there's not a unique opinion about that. It seems that the "air gap" between the heatsink and the PCH chip is by design, but as a matter of fact, Apple itself applied a lot of thermal paste everywhere, both on the CPU and on the PCH.
Good point, as potentially, there could be a benefit in not applying it on the PCH, as if it does not need to be heatsinked, heat could flow from the CPU to the PCH, increasing its temperature from an external source...
If I understand correctly, the temps I am measuring are quite normal, so maybe I should not worry too much 😅

 

[satcomer]

On such an older computer replace the thermal plaster on chip in Mac! This applies to other old machine as well, because that stuff seems to dry out over about 5 years!

 

[peterjcollins]

Yes, I replaced it, and it was quite dry!

 

[uller6]

I recently discovered this as well when I replanted repasted an old 2012 mini. I put some extra paste on to bridge the gap between the PCH and the heatsink. I figured it was fine for the 8 years it was in service with the original paste, so the chip should be fine as it is without a shim or other thermal pad. I agree that its a strange design decision.

 

[MBAir2010]

Ifixit has a step by step on how to heat sink a mac mini after installing an extra drive if that helps

 

[peterjcollins]

I recently discovered this as well when I replanted repasted an old 2012 mini. I put some extra paste on to bridge the gap between the PCH and the heatsink. I figured it was fine for the 8 years it was in service with the original paste, so the chip should be fine as it is without a shim or other thermal pad. I agree that its a strange design decision.

I did the same. I just added a bit of paste more on the PCH to make it touch the heatsink. I remember clearly that when I disassembled it, there was thermal past everywhere, both on the CPU and on the PCH, so I did the same...