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I'm planning to buy 2x4GB strips of DDR3 RAM at 1600MHz 9-9-9-27 (see here) The box that it is going in will be used to run virtual machines. This means that I may want to stick another 8Gb in it at some point.

I was wondering if I could get another two strips of RAM at some point and they would still play nicely together in dual channel mode. Do I have to buy the same make and model or just something very similar? Which factors are most important?

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with as many problems as people have with ram, you should at least try to get stuff that is as similar as possible. The controller it uses the configuration of the chips more important to similarity. The cute numbers actually not being AS critical as long as you manually control all that stuff yourself. which can go beyond the first 4 timing settings. – Psycogeek Oct 26 '11 at 23:39
up vote 1 down vote accepted

The only requirement for dual-channel mode is that you have the same amount of RAM on each channel. If you have 4GB on each channel or 8GB on each channel, the memory controller should run in dual-channel mode.

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+1 - Note: This is true unless it's a chipset that supports something like Intel's "Flex Mode", which allows RAM modules of different capacities to operate in a split dual channel mode. So 1x 512MB and 1x 1GB sticks in a dual-channel set of slots would give you 1GB in dual-channel mode (512MB from each stick), and the remaining 512MB on the 1GB stick would operate in single-channel mode. :) – Ƭᴇcʜιᴇ007 Oct 26 '11 at 20:32
@techie007 Also isn't recommended to get as close to matching RAM as possible? – CodeBlend May 10 '13 at 8:04

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