[gmx-users] Gromacs GPU system question

[Szilárd Páll]

I strongly suggest that you consider the single-chip GTX cards instead
of a dual-chip one; from the point of view of price/performance you'll
probably get the most from a 680 or 780.

You could ask why, so here are the reasons:
- The current parallelization scheme requires domain-decomposition to
use more than one GPU and the overhead of domain-decomposition is
quite high, so you typically get only 1.5-1.7x when going from one to
two domains (=GPUs, but you'll see that same with running CPUs only as
well);
- GROMACS uses the GPU as a coprocessor and needs to transfer
coordinates to the GPU and forces back; if your PCI-E is shared by two
GPUs which will inherently try to transfer at the same time, you'll
the overhead of transferring will get rather high (15% or more).

Cheers,
--
Szilárd


On Sat, Jun 22, 2013 at 5:31 PM, Mare Libero <mareliber27 at yahoo.com> wrote:
> Hello,
>
> I am assembling a GPU workstation to run MD simulations, and I was wondering if anyone has any recommendation regarding the GPU/CPU combination.
>
> From what I can see, the GTX690 could be the best bang for my buck in terms of number of cores, memory, clock rate. But being a dual GPU card, I was wondering if  there is any latency issue that could make its performances less favorable with respect to a GTX Titan.
>
> Also, which motherboard, CPU is recommendable for this system.
>
> Thank you in advance for you help,
>
> Al
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