I have an early 2008 Mac Pro. It currently has 6G of ram (2x1G and 2x2G sticks). I've been swapping with some programs for a while, and just got around to buying more ram. (4x4G).

My question is. . . am I better off just running the 4x4G or should I just add the 4x4G to the ram I already have? (my gut says more is better, of course just add, but I know there are often hardware considerations that may make this not true)

1 Answer 1


Considering you have Pairs of equal memory (2x1G, 2x2G and 4x4G) the best option is to install them all (that's a lot of RAM!).

Early 2008's Mac Pros use the full memory bandwidth when modules are installed in Pairs (like you have). But their location in the risers (where you install the modules) is important. Therefore, you should follow what the manual says.

Since you're going to fill all the 8 slots, you can go ahead an install them in pairs one next to the other. You have 2 risers, so here's how you should put them:


SLOT 1: 1x4GB

SLOT 2: 1x4GB

SLOT 3: 1x4GB

SLOT 4: 1x4GB


SLOT 1: 1x2GB

SLOT 2: 1x2GB

SLOT 3: 1x1GB

SLOT 4: 1x1GB

The graphic explanation for this can be read in the Early 2008 Mac Pro Memory Manual, located at manuals.info.apple.com.

  • Thanks for the info. I was just wondering if there were any gotchas as far as three different stick sizes etc. I don't really need more than the 16 that the 4x4 will give me, but I'll take the extra 6 if it won't make things slower.
    – skarface
    Mar 27, 2011 at 17:22
  • @skarface just add them all :) the more the merrier! Nice box you have there. I have the exact same machine, albeit with 10GB only ;) Mar 29, 2011 at 11:58
  • I didn't set out to buy 16G, but the ram prices have come down so much the amount I had budgeted in my head for 8 more let me get 16.
    – skarface
    Mar 29, 2011 at 13:31
  • @skarface it's ok, nothing to be ashamed of :) You'll certainly find 16GB to be an excellent choice to run memory intensive tasks. If anything, your VRAM will fall short before the real RAM. (I.e. if you want to run XPLANE and World of Warcraft at the same time) while having 10 applications open. Mar 29, 2011 at 13:48

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