CPU heatsink thermal pads thickness?

Discussion in 'Mac Pro' started by DIY_glenn, Sep 15, 2018.

  1. DIY_glenn macrumors member

    Joined:
    Sep 7, 2015
    #1
    Hi!
    About to replace the single CPU in my 2009 with a X5690. AFAIK no delidding necessary on single models.
    As I’m in there I’d also like to replace the pink thermal pads. Does anyone know the thickness?
    I have some 1mm leftover from redoing my GTX680.

    I don’t want to stack it to get 2mm etc, as I don’t believe that is the correct thing to do

    Anyone know the exact thickness of these pads? Length is probably not a problem, guess I could have multiple side by side?
     
  2. h9826790, Sep 15, 2018
    Last edited: Sep 15, 2018

    h9826790 macrumors G5

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #2
    If you want number, 2cc (volume) is the Apple recommended amount thermal paste amount.

    In real world, don't worry about it, there is no practical difference unless you apply "far too less".

    Practically, it's almost impossible to have "too thick" thermal paste (that's just a bad theory), thermal paste is quite liquify. When you tighten the heatsink screws, the extra thermal paste will be squeezed out. Of course, it will spread out, not a good practice. However, as long as the thermal paste itself is not electrically conductive. It shouldn't cause any problem, but just make things look dirty / untidy.

    TBH, it's really hard to get it wrong.

    https://www.pugetsystems.com/labs/articles/Thermal-Paste-Application-Techniques-170/

    If you really worry about "bad thermal paste application", you can go for the "always right" graphite thermal pad

    https://www.amazon.com/Innovation-Cooling-Graphite-Thermal-Pad/dp/B07CKVW18G

    This thing looks expensive, but re-usable, make it cheaper than thermal paste in long run.
     
  3. DIY_glenn thread starter macrumors member

    Joined:
    Sep 7, 2015
    #3
    Thank you for your reply.
    I guess I got the title wrong, I meant thermal pads. For the paste I usually just drop down a blob in the middle.

    That reusable pad for the CPU looked pretty cool though!
     
  4. h9826790 macrumors G5

    h9826790

    Joined:
    Apr 3, 2014
    Location:
    Hong Kong
    #4
    I see. I don't know the exact thickness of those thermal pad, but you can stack thermal pad.

    Due to it's characteristic (e.g. softness, stickiness, thermal conductive efficiency etc), AFAIK, there is not much difference between a single 2mm thermal pad and stack two 1mm thermal pads together.

    If anything need high performance cooling, it shouldn't use this kind of thermal pad at the very beginning.
     
  5. DIY_glenn thread starter macrumors member

    Joined:
    Sep 7, 2015
    #5
    I just disassembled it. Is has sweated a lot. The whole area is sticky, and it has gone through the holes in the board, and it is sticky underneath as well.

    Will do some light clean up (has gathered a lot of dust in the sticky parts).

    Seems to be 1.5mm thermal pad thickness.

    It’s not like any normal pads I’ve seen before. Looks more like cloth, but anything will probably work fine.
     
  6. Mac_User 0101 macrumors regular

    Joined:
    Oct 8, 2017
    #6
    Has the thickness been confirmed? 1.5mm doesn't sound right. I'd also like to replace the thermal pads on the voltage regulators next time I reapply thermal paste. There is nothing in the service manual about this. I have a 5,1 duel processor tray so I'm not sure if mine are different but they looked thicker than 1.5mm. I found the thermal grizzly pads online and they look similar but I just need to confirm correct thickness.
     
  7. Choppy23, Apr 30, 2019
    Last edited: Apr 30, 2019

    Choppy23 macrumors newbie

    Joined:
    Apr 10, 2019
    Location:
    Los Angeles, CA
    #7
    By default, the heat sinks come with 2mm thick pink thermal strips. This is fine if they cover the delidded CPUs on a 4,1 machine, but if you're upgrading to a lidded CPU, this will add another ~2.2mm that you will need to cover the voltage regulators with. Some people try to find a 5mm thick thermal pad (replacing the 2mm heat sink trips + 2.2mm in added CPU height). I have this one:
    https://www.amazon.com/gp/product/B07KX4K259

    This post has a lot of great detail. Scroll to the bottom of the post for detailed information on thermal pads:
    http://forum.netkas.org/index.php/topic,852.660.html#msg24313
    --- Post Merged, Apr 30, 2019 ---
    From the above netkas forum post:
    "1x Silicon Thermal Pad, of 3-3.2mm thickness for extension or 5mm for total replacement. Get 10x10 cm pads so that you have room to cut out the two strips you need (each strip you need is ~10cm long but not very wide). Many people that do this mod get 2mm pads but that's WAY too THIN and will leave airgaps, especially after compression, so DON'T use that or you won't sufficiently cool your voltage regulators meaning your system might die within a few years of use! Get 3-3.2mm pads, and just lay the 3mm thick pads on the voltage regulator chips, and they'll bridge the gap to the existing pink 2mm pads on the heatsinks. Some people try to find 5mm pads for a total replacement, but that's nearly impossible since it's a very uncommon thickness, and it's also more difficult since it requires gluing the new pads to the heatsink. The good news is that stacking a 3mm pad on top of the voltage regulators works perfectly and provides practically identical thermal transfer thanks to them being packed tightly together. I chose a 3.2mm pad of real silicon, which compresses itself to the perfect size and bridges the gap tightly. It's better to get a thicker pad than a too thin one which leaves airgaps and provides insufficient cooling!"​
     
  8. Mac_User 0101 macrumors regular

    Joined:
    Oct 8, 2017
    #8
    Thanks for the reply. 2mm is what I'll eventually need. It's for a real 2010 - 5,1 (not 4,1 updated to 5,1). I already upgraded my CPU's to duel X5690. They are lidded like the original CPU's that came with system. I don't think I could even use a delidded CPU on a 5,1 tray because of the way the socket clamps flush with the lid. The die would sit below the socket clamps and not make contact with the heatsink. Please correct me if I'm wrong about that.

    When I had the heatsinks off, I noticed a lot of dust stuck to the pink thermal pads. I picked what I could off with tweezers but I'll want to replace them in the future. Now I know what size to get. Thank you.
     
  9. Choppy23 macrumors newbie

    Joined:
    Apr 10, 2019
    Location:
    Los Angeles, CA
    #9
    Ah I need to retreat in my certainty then. All of my information applies to the 2009 4,1. The pink thermal strips on those heat sinks are 2mm. I don't know for sure about the 2010 5,1. They look the same to me in this detailed article, but I can't be sure:
    https://forums.macrumors.com/thread...-2010-quad-2-8-photos-new-cpu-to-use.1122551/
     
  10. Mac_User 0101 macrumors regular

    Joined:
    Oct 8, 2017
    #10
    Ok, I figured that. I think my best bet is to just buy a few thermal pads in 1, 2, & 3mm. That way I'll be sure to have the right ones when the time comes. They aren't super expensive and I'll end up using them for when I reapply paste to my video card. I'm a component cooling fanatic. I like a well cooled and quiet machine. Every two years or so I like to reapply thermal paste and pads. Even though the improvement is minor, it gives me peace of mind.
     

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9 September 15, 2018