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Made the mistake of thinking 12GB was enough, but I keep crashing out of memory while running sparse matrix solver... a few more GB should do it.

Is it valid to replace 3 of the 2GB modules with three 4GB ram modules, for 18GB total ? I realize that its "probably" valid, and "might" break triple-channelness, but does anyone have a specific experience trying this?

Mods- I think this is the same question, but unanswered and questionable choice of title... could be merged with my question. Semi-Hybrid Triple Channel DDR3

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peter karasev
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3 Answers3

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There's no rule that says your RAM all has to be the same size. Additionally you won't break "triple-channelness" so long as you have 3 matching 4GB dimms to replace the 3 2GB dimms.

It is important that the speed and timings are the same though otherwise your performance will be as good as your weakest component.

Hennes
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chunkyb2002
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In most cases, this sort of thing varies by motherboard. Most don't like too much mixing and matching, but can handle it in limited cases.

Mine, for example, has four slots. You're free to have two sorts of RAM, but slots 1/3 and 2/4 have to have identical sticks, otherwise Bad Things happen (slot 4 will be ignored, IIRC). This would obviously be a bit different with triple-channel, but the same principle applies.

My advice would be to check your mobo manual, try it and see what happens., and if it doesn't work, look into getting 2 or 4 of the 4GB sticks for balance.

ssube
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To dig up an old topic: as the x58 chipset is getting renewed attention and there is a lot of “hear say” about optimal memory configurations, I would like to inform you about my own experiences and tests.

I can confirm that a 3x(4+2gb) configuration is fine on the x58 chipset, and works in true triple channel, as does a 2x(2+2gb)+1x(4Gb) config.

My advise is not to listen to hear say, and to do your own research. In that way, I found out it is fine to mix and match different memory sizes and types, as long as they can make the same timings (weakest link determines the lowest timings). To preserve triple channel, you should achieve the same size PER CHANNEL. So it is fine to mix 2x2gb sticks on channels And B, and to use a single 4Gb stick on channel C. But it is not fine to use 4 4Gb sticks! Please use a benchmark tool for comparison. In the latter case, my ASUS p6t deluxe v2 reports 5,33 gb triple channel, but performance is crippled, because 1 stick is used for interleaving. When I use 3x (4+2=6gb) = 18gb, performance is much better (triple channel worthy), despite the uneven sizes. Conclusion: mixing and matching is fine on x58, as long as everything comes in 3’s. (4+2)x3 or (4+4)x3 or (8)x3. Please be advised and only believe the benchmarks!

Builderman
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