Another Memory Question

Discussion in 'Mac Pro' started by Phillie14586, Jan 18, 2011.

  1. Phillie14586 macrumors member

    Oct 14, 2010
    I have a 2010 single processor quad core so it only have one memory riser. Am I correct in that the memory needs to be installed as 3 of the same with nothing in the 4th slot or as one or two pairs? So 2x4G + 2x1G will work but 3x4G + 1x1G would not.
  2. DeeEss macrumors 6502a

    Jan 17, 2011
    As far as I know, everything works but 3 of the same, ie. triple matched memory works best. You can stick a 4th in and it will certainly help if you need that much, but 3 works best apparently.

    For example 4x3gb (12gb) is faster that 2x8gb (16gb)
    I read that 32gb is actually slower than 24gb, but if you need 32gb of RAM then it will stop the computer from being sluggish.
  3. Stephen23 macrumors member


    Jan 8, 2007
    Austin, TX
    The performance hit for using that 4th slot is only 2% - 3%, and that only applies if you're not actually using all of the available memory. If your system gets to the point that it's using all 24GB, then that 4th slot is going to help immensely.

    Phillie - As far as I know, either of the examples you site should work, but you'll get far better performance if you stick with three of the same type, or if you need all four slots, four of the same type.

    The sweet spots are 6GB (3x2GB), 12GB (3x4GB), and 24GB(3x8GB). If you use your machine like the average user, the best price/performance configuration right now is the 12GB. Paying for the 8GB sticks really only makes sense if you work with large files and use a lot of memory, or are pretty sure you will in the near future.
  4. gpzjock macrumors 6502a

    May 4, 2009
    Do you want frying with that sir?

    I would recommend this RAM instead:
    It has the Apple recommended heatsinks on it to help prevent overheating memory. My RAM runs at 70-80ºc at peak use with the heatsinks on and over the last 3 years I have had to RMA replacement RAM that has failed. Fortunately the vendor supplies a lifetime warranty so it only costs me shipping.
  5. johnnymg macrumors 65816


    Nov 16, 2008
    My 2010 MP came with "naked" mem modules so I guess Apple doesn't use that recommendation.

  6. gpzjock macrumors 6502a

    May 4, 2009
    Interesting, how are your temps? I suspect they have improved the cooling in that case. :)
  7. johnnymg macrumors 65816


    Nov 16, 2008
    25-28 C with a room temp of ~18 C. This is for the replacement 4x4GB modules.

    FWIW, the Northbridge temp is 35 C.

  8. diazj3 macrumors 6502a

    Jan 19, 2008
    70-80ºc ram?!? isn't that way too high, even at peak use?... I'd recommend you either check your machine, or install other RAM just to check it's not defective and the thermal sensors are working properly.... just my 2 cents.

    The price difference between different RAM brands/vendors is so marginal - specially with large amounts - that I'd rather go with OWC. I like their mac focus and customer service.

  9. gullySn0wCat macrumors 6502

    Dec 7, 2010
    The heat spreader recommendation doesn't apply to 2010 Mac Pro because they don't use FBDIMMs.

    70-80 degrees under load is still within the correct operating temp for the kind of memory in older Mac Pros. I usually get 60+ in slot a1 (it has worse airflow) then 50-60 idle in the other slots, which usually goes up to 70 under load.

    My Northbridge temperature is 65 now. LOL!
  10. Phillie14586 thread starter macrumors member

    Oct 14, 2010
    Thanks for the replies. I do Lightroom, iMovie and use the computer as a home theater recording and playing recorded TV. It came with 3x1G so I was thinking of going with 2x4G and use 2 of the 1G sticks for a total of 10G. If I go to 3x4G and not use one of the 1G sticks then it is about $75 for those last 2G. My break point is $75 for 3G but that would mean using the 3x4G then a 1G stick in the fourth slot. So I was wondering if I take a hit for running dual channel and another hit since one pair would not be matched or would it run as triple channel plus 1 stick?
  11. gpzjock, Jan 19, 2011
    Last edited: Jan 19, 2011

    gpzjock macrumors 6502a

    May 4, 2009
    Nice to see they fixed the airflow.

    Thanks for the temp info Johnny, it would appear that Apple have vastly improved the airflow round the memory boards and switching from FBDIMMs has reduced the heat generation significantly.
    I assume the change was an evolutionary process and the improvement in temp has helped with the RAM failure rate. :)

    I'd go with 3x4gig tbh, screw the expense.
  12. Vylen macrumors 65816

    Jun 3, 2010
    Sydney, Australia
    I suppose so... since Nehalem (2009), they did away with the riser cards and now the CPU and RAM are on the same daughterboard. Consequently, airflow doesn't go from the front, through the CPU heatsinks, then the riser cards and out the back on the FBDIMM systems. Instead, air goes past the CPU and RAM simultaneously... as so to describe it.
  13. gpzjock macrumors 6502a

    May 4, 2009
    I haven't had a daughter card with a CPU on it since my Bondi Blue iMac in 1998 :D

Share This Page