Mac mini upgrade Core2 Duo runs WAY too hot, >90C

Discussion in 'Mac mini' started by NatronB, Jan 27, 2011.

  1. NatronB macrumors regular

    Jul 2, 2002

    I upgraded my Mini Core Solo to a 2.0 Ghz Core2Duo, maxed out the RAM and put in a WD 500 GB drive. All work fine, but now the mini runs VERY hot. Right now it's at 85C with only a 15% processor load, the fan at 3500 RPM, on a stand and with the case off (to promote airflow). If I try to run more CPU intensive apps, the temperature quickly goes to 100C and the fan maxes out. HD = 29C, Heatsink = 33C, Ambient= 29C. OS 10.6.6.

    I've applied and reapplied thermal paste (cheap stuff from Best Buy), replaced the stock nylon heatsink pins with nylon screws, which seems to give a snug fit between the processor and heatsink. I'm thinking about getting a laptop cooler to help out, but I can't help but think that I've done something wrong.

    If anyone has any hints, I'd love to hear them.

    Thank you,

  2. Hellhammer Moderator


    Staff Member

    Dec 10, 2008
    If you bought some crappy thermal paste, that might be causing the issues. I would try applying better thermal paste, it only costs like 10 bucks
  3. Intell macrumors P6


    Jan 24, 2010
    I've done the same upgrade you have. My Mini isn't overheating, in fact the temperatures are almost the same. I see that there it a huge difference between the CPU and heatsink. My guess is that you haven't put the heatsink on correctly. If I remember correctly, the heatsink goes on only one way. Also try it with the case on. Remember, it was designed to work with the case on. And with it on the fan has the most cooling power.
  4. alust2013 macrumors 601


    Feb 6, 2010
    On the fence
    Yeah, like intell said, if there is such a discrepancy between the CPU and heatsink, something isn't right. Either the thermal paste really sucks or the heatsink is on wrong.
  5. belvdr macrumors 603

    Aug 15, 2005
    OP, also remember:

    1. Apply a very thin coat. The thermal paste should not even be 1mm thick. I put a small dot on the processor and spread it out. Then also apply some to the heatsink and spread it out as well. The goal here is to have the paste fill in any microsopic gaps in the metal .
    2. The only parts that should get thermal paste are the parts that touch. It should not be all over the processor.
    3. Make sure your heat sink is secured.
  6. NatronB thread starter macrumors regular

    Jul 2, 2002
    Thanks for the tip, but if the heatsink is positioned incorrectly (90 or 180 degrees rotated) the drives won't fit on top correctly (trust me, I did it twice incorrectly before).

    I'm leaning towards the crappy thermal paste. At the same time, I'm finding it hard to believe it makes THAT much of a difference. Finally, running it with the case on doesn't change things that much.

    Thanks to everyone who responded,

  7. davids8477 macrumors 6502

    Jan 4, 2008
    I did the same upgrade and had the same problem.

    My issue was not applying the thermal paste correctly (see other posts in the thread) AND not tightening the heat sink scres in an even manner.

    Did that and now at idle (in 70 F room in closet) it is running at 120F
  8. NatronB thread starter macrumors regular

    Jul 2, 2002
    Thanks, I did use a very thin coat, only on the spots it's supposed to be on.

    One thing I neglected to mention is that I used replacement nylon screws I got from the hardware store, that I then had to whittle down. It's a less than ideal fix, but the processor feels snug. Where can you get replacement (purpose built) screws online?

  9. belvdr macrumors 603

    Aug 15, 2005
    That could be the problem, especially if the heatsink is not held tightly against the processor.

    You might check iFixIt or OWC to see if they have replacements.
  10. davids8477 macrumors 6502

    Jan 4, 2008
    I dont think the originals are screws - more like a barbed clip. Mine broke when I removed them and I replaced them with nuts and bolts - being very careful not to short anything on the circuit board.

    I think you have found your problem.
  11. NatronB thread starter macrumors regular

    Jul 2, 2002
    You're right, the originals are clips. I, too, broke them when I took them out.

    And, I'm sorry, I used nylon bolts, not screws, that I had whittled down.

    When you say 'nuts and bolts' do you mean metal nuts and bolts? I'm a little apprehensive about this. Should I not be?


  12. davids8477 macrumors 6502

    Jan 4, 2008
    Well I did a dry run with the METAL nuts and bolts to be sure there was no possibility of shorting. I read somewhere on the web that the breaking clips is a well know issue and on that page the writer suggested to correct size nuts and bolts (and washers).

    If you use nylon then there is no electrical issues of course, but are you also using nuts? I tightened my heatsink down really well and if you do not use a nut then I don't think you can do that - as the originals were clips - and therefore no thread for your whittled bolts to bite into.
  13. NatronB thread starter macrumors regular

    Jul 2, 2002
    Okay, I'm going to sound foolish, but hear me out: I wasn't using nuts, but the threads of the nylon bolts were catching on the board. In hindsight, it's clear to me that the heat sink simply isn't tight enough with the processor. I'm going to try metal nuts and bolts this evening.

    Thanks for the help,

  14. hwojtek macrumors 65816


    Jan 26, 2008
    A small rural village in western Poland
    Remember to use some isolation washers, so the metal nuts and bolts won't touch the motherboard directly.
    I did a 1.66 CD -> 2.33 C2D upgrade and noticed the temps even a bit lower than before the upgrade. Managed not to break any original bolts and used Arctic Silver thermal paste. When putting it back together I was actually afraid I am going to crush the CPU with the heatsink, but I didn't and it works this way for almost 3 years now.
  15. Spanners macrumors member

    Feb 21, 2006
    Tunbridge Wells, UK
    So - I too have done this upgrade - broke the pins and replaced with nylon screws and bolts and have found the following,

    Ambient temp is about 60 deg c
    Under heavy load is about 90/95 deg c

    I've also started getting random freezing.

    I'm looking for any good suggestions as to where I may have gone wrong? I think I applied about the right amount of thermal paste and although its not the expensive stuff I did use the following

    Any ideas - paste not good enough or should I really tighten down the screws (although I thought it was pretty damn tight)?
  16. NatronB thread starter macrumors regular

    Jul 2, 2002
    my solution....

    I was able to resolve my issues with a two-prong approach:

    1) Cleaned off the processor and heatsink and used Arctic Silver.

    2) Used metal 4/40 nuts and bolts with nylon washers on both sides. Tighten as much as you possibly can.

    This is a less than ideal solution, obviously. If I could've found nylon 4/40 screws, I would've used them. My computer is running FAR cooler now though, topping off at 65C.

    Good luck,

  17. sascha h-k macrumors 6502

    sascha h-k

    Apr 26, 2004
    vienna / austria
  18. a4ex macrumors newbie


    Jun 29, 2011
    I have a mini late 2009 and since i installed Lion I get temps up to 93 C.


    I'm afraid that because i leave in a very dusty environment the airways are clogged thus i'm having the problem.

    But i'm very skeptic of opening up my mini.
  19. cluthz macrumors 68040


    Jun 15, 2004
    Compressed air is your friend!
    You can probably buy small canisters at you local computer store.
  20. a4ex macrumors newbie


    Jun 29, 2011
    I have a blower and i did it a couple of weeks ago but it seems it didn't help. I'll get compressed air canister and i'll try also to open it.
  21. philipma1957 macrumors 603


    Apr 13, 2010
    Howell, New Jersey
    link for nylon parts

    many other choices then the two i gave you

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