3

All 3 modules will have the same MHz but how do distribute modules to best handle multi-channel RAM. When buying 8GB is easy as I can take 2 x 4GB.

What solution is best for 12GB:

  1. 3 x 4GB
  2. 8GB + 4 GB
  3. something else?

If not absolutely the best solution, I would not go with 3x4GB since in the future I will probably have to throw away one of these 4GB modules when upgrading to more RAM due to the lack of RAM slots. Things like this happened 10 times so far.

Improve this question
2
  • 3
    What CPU and motherboard are you using?
    – Benjamin Barenblat
    Dec 1, 2013 at 21:47
  • 1
    Note that multi-channel RAM is the same as ordinary RAM. It is just sold in bundles and tested to be compatible. The multi channel access part is in the memory controller(s).
    – Hennes
    Dec 1, 2013 at 22:12

2 Answers 2

Reset to default
5

It depends on the memory controllers.

If you have one CPU and it:

  1. Only supports 'normal' memory access: Then it does not really matter.
  2. If the memory controller supports dual channel, get the memory in pairs. They can be used at the same time. For 12GiB that would be 2x4GiB and 2x2GiB
  3. If the memory controller supports triple channel, get 3x4GiB (e.g. on an i7-920 Nehalem)
  4. If the memory controller supports quad channel, get sets of four identical DIMMS. E.g. 4x 2GiB and 4x 1GiB.
  1. If you have multiple CPU's (chips/sockets, not cores), each with their own memory controller, then fill each of those. E.g. on a dual Xeon W3520 you have two CPU's. Each with its own triple channel option. So get 6 DIMMS (2x3 channels, for 6 2GiB DIMMs).

If you have an option to fill all channels with either one set of DIMMs (e.g. triple channel and 3x4GiB) or with two sets of DIMMs (example. same triple channel setup with 6 DIMMs) then my own choice would be the lesser number of DIMMs. Both to keep expansion options open and because less ranks per channel allows higher bus speeds. (And thus allows you to use XMP).

Improve this answer
4
  • Seems 12GB of RAM is a bad idea. Too many slots occupied for not so much performances.
    – JoeM
    Dec 2, 2013 at 11:14
  • In almost all cases 12GiB is better then 8GiB (And 16GiB is even better).
    – Hennes
    Dec 2, 2013 at 14:57
  • Yes if you have performance in mind. But later if all slots are occupied and I want to upgrade, I have to throw away 2GB module and install 4GB ones.
    – JoeM
    Dec 2, 2013 at 18:55
  • Correct. Not that you gain that much performance. For a typical home user going from single channel to dual channel increases most programs by a few (5-ish) percent. The only time it gets really important is when your programs manage larger data-sets than fits in the L2 or L3 cache. Or when you have relative slow memory (e.g. DD^ at 533MHz as with the origional X58/i7 Nahelem setup and you need to feed 6 cores with a lot of memory access. (The example chipset has triple channel which is barely any faster than dual channel when used with its most common CPU, the I7-920.)
    – Hennes
    Dec 2, 2013 at 23:51
1

On a dual-channel motherboard with four slots it would be 2×4GB and 2×2GB.

This is the only configuration for 12GB in dual-channel since RAM is only produced in powers of two (unless you have more slots).

Improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .