no. of CPUs for optimal GTX-690 performance

From: Michael Purdy (
Date: Tue Nov 06 2012 - 13:01:41 CST

Hello, I am running NAMD simulations (multicore-CUDA) on a ThinkPad with
dual Core i7-2760QM CPUs and a Quadro 2000M running Debian. For a 150k
atom system I get performance like this:

Benchmark time: 4 CPUs 0.287062 s/step 1.66124 days/ns 387.641 MB memory
Benchmark time: 7 CPUs 0.289229 s/step 1.67378 days/ns 428.574 MB memory

Things are going well so we purchased a GTX-690 which we installed in a
workstation with two dual core Opterons, which is evidently far short of
the CPU cores we need to get the most of the 2 GPUs and 3072 cuda cores.
Performance was just slightly better than the ThinkPad:

Benchmark time: 4 CPUs ~0.2 s/step ~1.4 days/ns

We would like to build a new workstation to get the most out of the
GTX-690 and I'd like to know how many CPU cores we need. I'm considering
two Core i7-3930k (6-core/12-thread) or two Xeon E5-2650
(8-core/16-thread). Will either of these be a good match for the GTX-690
or will I still be short running short on CPUs? The current plans is to
build this on an Asus Z9PE-D8 WS board.


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