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When 16GB RAM isn't enough

1

12dylan34

macrumors 6502a
Original poster
Sep 3, 2009
884
15
A few quick questions abut using more than 16GB of RAM in the 27 inch iMac.

To begin, I know that I need more than 16GB for sure. I use a Mac Pro at work that has 16GB and page outs are at about 5GB after a day's work. I'll be putting my personal machine up to a similar load with all of the same software. This leads me to believe that I need more than 16, but probably less than 32. I'd like to not spend more money than I need to.

So, let's assume that the new iMac can accommodate 32GB and comes with 8GB standard, in a 2x4 GB configuration.
  • Will it work to just buy 2 8GB sticks for a total of 24GB including the memory it came with?
  • Is mixing brands and different sized sticks an issue? If not, is there a certain way that I want to arrange them in the 4 slots that the iMac has?
  • Unrelated, but does the iMac come with a thunderbolt to VGA/DVI adaptor?
Thanks for any help that you may be able to provide.
 
no one knows about the new iMac

"Unrelated, but does the iMac come with a thunderbolt to VGA/DVI adaptor?"
no it doesn't
 
charlieegan3 said:
no one knows about the new iMac

"Unrelated, but does the iMac come with a thunderbolt to VGA/DVI adaptor?"
no it doesn't
Click to expand...

Well, this would apply to the current iMac as well then. Really any computer with 4 RAM slots. Thanks for the adaptor answer though.
 
Like dudeguy said above, no one knows about the new iMacs just yet. But...

12dylan34 said:
Will it work to just buy 2 8GB sticks for a total of 24GB including the memory it came with?
Click to expand...

If it's got three or more slots, then yeah. But there are a few things you'll want to keep in mind, which I'll answer with your next question...

Is mixing brands and different sized sticks an issue? If not, is there a certain way that I want to arrange them in the 4 slots that the iMac has?
Click to expand...

Yes, you can, but it's not the most optimal setup. Various makes and models of ram even among the same class (ie DDR3 1333) usually have different timings. On the PC at least, the bios will try to find the closest matching clocks between the two, which is very rarely the best you can get. Mixing ram can give you a slight to moderate performance hit depending on what the bios sets as that happy medium.

Plus if you don't use the same size, make, and model of ram, you won't be able to take advantage of triple channel memory, giving you another slight to moderate performance hit.

So it works, but it won't give you the absolute best performance you can get. Better just to go all out and get matching ram from the start instead of mixing and matching later.
 
Renzatic said:
Like dudeguy said above, no one knows about the new iMacs just yet. But...



If it's got three or more slots, then yeah. But there are a few things you'll want to keep in mind, which I'll answer with your next question...



Yes, you can, but it's not the most optimal setup. Various makes and models of ram even among the same class (ie DDR3 1333) usually have different timings. On the PC at least, the bios will try to find the closest matching clocks between the two, which is very rarely the best you can get. Mixing ram can give you a slight to moderate performance hit depending on what the bios sets as that happy medium.

Plus if you don't use the same size, make, and model of ram, you won't be able to take advantage of triple channel memory, giving you another slight to moderate performance hit.

So it works, but it won't give you the absolute best performance you can get. Better just to go all out and get matching ram from the start instead of mixing and matching later.
Click to expand...

Thanks for the detailed reply! I'll probably just get 32GB new then.
 
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