RAM questions on upgraded 2009/2010

Discussion in 'Mac Pro' started by scenemissing, May 6, 2015.

  1. scenemissing macrumors member

    Jun 18, 2010
    Hey guys - I had a couple of RAM questions on the box I've been working on. I did a little Google searching, but just wanted to make sure I wasn't crazy before making the purchase. I recently got a 2009 Mac pro off a friend of mine. It was a standard quad 2.66 with 6GB ECC ram. I successfully did the 2010 firmware crossflash and upgraded to a hex core Xeon 5650. So far that's working well, but I need some memory to go with it.

    I read that the new chip can support non-ECC as well as long as you don't mix types. Is that advisable for large amounts of ram? I was about to but 24 GB of non-ECC regular old PC1333, but I wanted to ask around to make sure it was wise. Normally this box is just going to be a regular home server, but the reason I wanted so much ram is that I'm studying for some VMware certs and I wanted to have a home machine I could run the labs on. It would be running ESXi in a nested config within VMware Fusion 7. Those servers would never actually be production in any way, I just need to set them up, configure them, and use the VMs to study for my VCP exam.

    I read in a few places that these chips run best in tri-channel mode, that's why I'm going with 3x8GB instead of 4x4 or 4x8. I was preferring to buy the non-ecc because it's cheaper and faster, but wanted to check if that would be unstable.

    tl:dr - is 24GB of non-ecc DDR3 going to give me problems on a 2009>2010 upgrade box?
  2. avemestr macrumors regular

    Aug 14, 2012
    No. I've been running such a setup in such a machine for about 3 years with no problems whatsoever.
  3. h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    It should be fine. I am running 4x8G non ECC RAM now, no problem at all.

    And yes, triple channel will give you better RAM performance, but the difference is negligible in most of the real world usage. For VM, more RAM should still better than faster RAM config

    Of course, you can start with 3x8G, and only if that still not enough, then further increase to 4x8G.
  4. scenemissing thread starter macrumors member

    Jun 18, 2010
    Thanks guys, I will order the ram today. Appreciate it!
  5. Parigot macrumors member

    Oct 22, 2011
    I ordered my RAM for my 4.1 from memoryx.com. They had the ECC one with the thermal sensor for a reasonable price. Works great!
  6. ZombiePhysicist macrumors 6502a


    May 22, 2014
    I think, at least for 5,1 machines, you can go to quad channel with no performance hit, when using at least some kinds of memory. I think I saw Macvidcards successfully used all 4 channels and his memory stayed at 1333mhz, and have had similar success here as discussed here:


    TLDR, if you use some times of non-mixed memory, you can use all 4 banks of memory in a 5,1 machine with no performance penalty. Not sure if this applies to a 4,1 that was flashed into a 5,1...
  7. flowrider macrumors 603


    Nov 23, 2012
    When you fill all 4 slots you are not going quad channel, as you call it. The CPU still has triple channel memory. On the Mac Pro, the third and fourth slots are electrically coupled - It's just an extension of the third channel. Also, if you populate slots 1, 2, and 4 - slot 4 will not be recognized.

  8. ZombiePhysicist macrumors 6502a


    May 22, 2014
    Thanks Lou, did not know that. Regardless, if you put in all the same memory as noted in the other thread, even if you fill all 4 slots, you'll maintain the same speed. That is doable, and I think the old common knowledge was that it wasn't doable. So it's a bit of you can 'eat your cake and still have it too' news. :)

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