On Wed, Apr 8, 2009 at 2:49 PM, Peter Kjellstrom <c...@nsc.liu.se> wrote:
> Can anyone confirm that mixing different sizes of dimms, even when keeping > to > a by-three-symmetric configuration, actually does degrade performance? > > That is, first hand information that config 1 will be slower than config 2: > > 1: two sockets, 3x 1G and 3x 2G per socket RDIMM (total 18G @1066) > 2: two sockets, 6x 1G(or 2G) per socket RDIMM (total 12G (or 24G) @1066) No, it does not degrade performance as long as the CAS latencies of both DIMM types are identical and you would not get a clock-down by using that quantity of RAM ranks. We have been able to attain Intel's reported, magical 35GB/s number using ICC. GCC 4.3 is around 31GB/s. (At 1333MHz.) We're a little reticent to approach this, though. It's certainly easier to explain whole units of divisible RAM quantities to customers. The whole tri-channel memory thing is already hard enough to have a conversation about. Especially when people write their specs as X GB of memory per core--where X is power of two.
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