Heatsinks on Mac Pro RAM?

Discussion in 'Mac Pro' started by warragul, May 28, 2017.

  1. warragul macrumors member

    Sep 19, 2016
    Melbourne, Australia
    Bought a Mac Pro online. 2008 2X2.8GHz 8-core. Runs El Capitan, but not (unmodified) Sierra.
    There are a couple of upgrades I’ve looked into but the one that’s bothering me now is RAM.
    I’ve bought 32Gig of the right stuff but it came without “heat spreaders”. Why we needed a new
    name for heat sinks is beyond me. And why not “thermal dissipators? :)
    The available literature is very confusing on this. Do I need them or do I not?
    Apple has a Tech Note TN 2156 that says they are necessary, if only to keep fan speeds in check.
    Interestingly, there is a reference in the Tech Note to MO-256 FBDIMM Heatsinks.
    New heat spreaders of that design cost as much, if not more, than the RAM.
    On the other hand Tom’s Hardware says they are only necessary if you’re overclocking the RAM.
    The “heat spreaders” selling online are way flimsier than the Apple Approved ones that came with
    the RAM installed on the Mac Pro. The only option I see is to transfer the “spreaders” from the
    installed RAM to the new stuff. Then there’s the thermal conducting plastic adhesive strips to consider.
    If they behave like normal double-side tape things are going to get messy.
    Anyone got any better ideas/info/experience?
  2. fendersrule macrumors 6502

    Oct 9, 2008
    Just from second hand (grain of salt) you do not need them.
  3. Sko, May 29, 2017
    Last edited: May 29, 2017

    Sko macrumors 6502


    Oct 17, 2009
    I bought cheap RAM off of eBay with heat spreaders and it really sucked. RAM temperatures were almost always north of 80°C - that's where the fans kick in on my 2,1. I tried to mount different heat spreaders, thermal paste and thermal pads. I had to learn that most of the time it just wouldn't fit. The AMB was never flush with the actual RAM chips, there was always a gap between the HS and the AMB or the HS and the RAM chips.

    I decided to go another route and bought some very, very cheap server pull 4 GiB RAM modules from a local IT service company. It came in sets of four, so I bought two sets, one label as Dell and one as HP.

    The temperatures where exactly on the edge, hitting 80°C every so often. What I finally did was adding tiny HSes directly on top of the AMBs with thermal conductive adhesive tape. Now I have temperatures in the low seventies.

    Long story short: some tinkering may be required with or without the large Apple-style heat spreaders.

    Attached Files:

  4. warragul thread starter macrumors member

    Sep 19, 2016
    Melbourne, Australia
    Thank you, Sko. Just what I needed. I saw those small heatsinks when I was searching eBay for heatspreaders.
    Never occurred to me that cooling the AMBs would be enough.
    Again, thanks.
  5. orph macrumors 65816

    Dec 12, 2005
    i think it's fairly normal for people to use puled server ram in 1.1/2.1/3.1 and 667mhz speed too as it's cheaper with minimal slowdown.

    cool idea sticking on some extra heat sinks @Sko
  6. ReanimationLP macrumors 68030


    Jan 8, 2005
    On the moon.
    I did the same exact thing @Sko did in my 3,1. No issues, prevents the fans from ramping up.

    Of course, now I'm about to retire it for the 4,1 I got for cheap once I drop X5690s into it... unfortunately the seller didn't pack it properly so the handles got smashed, but he refunded me about half the cost of the computer.

    Spent almost as much on eBay for a case that's not messed up as I did on the computer. lol
  7. EmlynDewar macrumors member

    Aug 17, 2011
    Chengdu, China
    Think there's not too much you can do with DDR2 FB-DIMMs, they've always ran as hot as the sun and needed some airflow to avoid death!
  8. AlexMaximus macrumors 6502a


    Aug 15, 2006
    A400M Base

    The 2008 Mac Pro is still an awesome machine. For proper cooling, I would just add a ram cooler. You may want to consider this one here, its the only one that works for the Mac Pro.


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