64GB RAM Upgrade for Mac Pro 3,1 (Early 2008)

Discussion in 'Mac Pro' started by outatime, Apr 15, 2017.

  1. outatime macrumors newbie


    Apr 15, 2017
    Hi there,
    I wanted to upgrade the RAM of my old Mac Pro 3,1 - 2x4 Quad Intel Xeon (Early 2008) up to 64GB of RAM. At this moment, I have 10GB of 800Mhz Kingston RAM installed and with El Capitan 10.11.6 and Adobe CC. It's definitely to slow now.

    I'm not sure, if I should go for 8x8GB 800Mhz which is installed right now or better take the 667Mhz. I read somewhere, that it is not recommended to use the whole 64GB of RAM. Is that true?

    Is this ebay offer here good? I have no experience with used and refurbished components, but the price looks good.


    Thanks in advance

    Best outatime
  2. jeeplj8 macrumors member

    Jan 4, 2014
    One of the reasons I wanted to upgrade from 3.1 was the memory bus limited to 667. That looks like similar server based memory that I put in my machine several years ago. I went to 32GB and it made a pretty big difference. My new 5.1 has 64, but I have not really stretched its' legs yet.

    It does not matter if you put 800mhz or 667, it will still run at 667, so really whatever is cheaper.
  3. outatime thread starter macrumors newbie


    Apr 15, 2017
    Ok, thanks. You mean the 3,1 hardware limits it speed anyway? Ok, then i will go for this ebay offer, 159€ for 64GB sounds fair.
    --- Post Merged, Apr 15, 2017 ---
    The question is, if this cheap RAM is trustworthy. I spend money for my Kingston RAM in 2009 and it was quality stuff. But now i dont want to spend too much for this old computer. I found this answer in a apple forum thread:

    "Don't buy the cheapest RAM you can find. There's a reason why it's cheap, usually because it won't pass anyone else's certification tests (such RAM is referred to in the industry as "floor sweepings"). If you can't afford RAM from a reliable vendor (search this forum for "RAM UK" and you should find a number of recommendations), hold off until you can afford to buy quality parts. Bad RAM will cause you nothing but grief, and while it's not guaranteed that RAM from a "cheap parts vendor", getting bad RAM is more likely from such a vendor. Better to run your system with less RAM than would be ideal for best performance than to struggle with flakey RAM."
  4. Flint Ironstag macrumors 6502a

    Flint Ironstag

    Dec 1, 2013
    Houston, TX USA

    Not quite. If you populate the 3,1 with only 800MHz sticks, they will all run at 800. If you mix and match, they all run at 667. It's been a long time since I've seen the benchmarks, but I recall the difference was negligible and not worth the cost.

    Me, I like running the correct speed. Make sure you've upgraded your SSD too if you haven't already.
  5. outatime thread starter macrumors newbie


    Apr 15, 2017
    Thanks, will go for the 667 then. Its hard to find a 8x8 set for a good price. Yes, SSD is also on my list. Is there a special SSD, which can be recommend for this old kind of computer with a cartridge?
  6. jeeplj8 macrumors member

    Jan 4, 2014
    you can mount any sata ssd you like. There are two ways. you can drive an adapter buy ebay or owc that allows you to mount a 2.5inch ssd in the apple factory HD tray, or you can do what I did which was place a small piece of foam on the front fan assembly to hold an SSD in the slot for bay 1 only on the 3.1.

    Actually a third way, you can use the power in the optical bay with a ide to sata power converter and run a sata cord to the motherboard. you can actually add 2 additional SATA drives on the 3.1 this way.
  7. nigelbb, Apr 26, 2017
    Last edited: Apr 26, 2017

    nigelbb macrumors 65816

    Dec 22, 2012
    I have a 2 x 3.2GHz 8-core 2008 Mac Pro 3,1 with 56GB using 6x8GB & 2x4GB FB-DIMMs. The RAM is all 667MHz. AFAIK only Apple used 800MHz FB-DIMMs & never shipped 8GB parts. Performance is great for a nine year old system with the other enhancements 2x1TB SSD in RAID-0 on PCIe plus flashed 4GB GTX680. There is a quirk that if you fit 64GB of RAM in a MP 3,1 then performance of PCIe SSDs is halved so if you have one of these devices then 56GB is the maximum RAM you should fit & still get full performance. Details here https://forums.macrumors.com/thread...e-48-gb-fast-disks-why.1940030/#post-22338450
  8. outatime thread starter macrumors newbie


    Apr 15, 2017
    Thanks, thats interesting. I still have to replace my old HDD into a SSD and i build in 56GB of RAM yesterday, because with 64GB, the MAC Pro is getting real hot.
  9. ssgbryan macrumors 6502a


    Jul 18, 2002
    The 3rd way is what I did with my 1,1.
  10. AlexMaximus, Apr 28, 2017
    Last edited: Apr 28, 2017

    AlexMaximus macrumors 6502a


    Aug 15, 2006
    A400M Base
    On the SSD issue, there is one very important point you should not ignore. With a simple SATA SSD (first gen) your speed advantage would be only "mediocre" because of limitations of the slow sata bus. At this point & time in the game, you really should use a PCIe card with a blade / flash SSD. My advice: Go for a samsung 951 AHCI SSD blade with an Anglebird PX1 pcie adapter card. Heat is an issue in the MP3.1 so you will need that heat sink. If you can not find the 951 ahci one any more, the alternative would be a HyperX Predator. There is also a HX Predator "all in one kit" available with pcie card attached, however you would still need to find a heat sink yourself.



    .. to prevent ram heat stroke..

  11. outatime, May 2, 2017
    Last edited: May 2, 2017

    outatime thread starter macrumors newbie


    Apr 15, 2017
    Thanks a lot for the advice, the heat problem is solved now. One FB-DIMM was not working and I replaced it. Now everything is running on a normal Level and 64GB seems to run stable.

    Now I'm going to replace my system-HDD. I still have the original WD HDD 320GB in use. I want to replace it for a Samsung SSD 850 EVO MZ-75E500B 500GB, which seems to be a good price. Hope it will interact without problems with the old "667" RAMs, like you mentioned.

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