Re: Advice on buying GPUs

From: Ajasja Ljubetič (
Date: Thu Jun 02 2011 - 08:27:47 CDT

> this is not that easy to answer and 20k EUR is a pretty small sum.
> question is, how much are you interested in compute capacity (more nodes)
> vs. capability (ability to run jobs faster)? do you already have an
> infiniband
> (or similar) switch that those nodes could be added to? also, what kind
> of facilities do you have (cooling, power, racks, storage)?

Oh, what we have is what I build two years ago. No sales reps were involved
in the process:) it will probably make you laugh, but still, a laugh a day
is healthy, so here it goes:
We have the 8 nodes allready mentioned:
8x tyan mother board <>
16x AMD Opteron Quad
8x 750 W PSU
connected with gigabit ethernet and cooled by air. External air is blown at
the bottom and sucked out at the top. Without the cover the "cluster" looks
like this <>.

Currently I'm doing some ABF stuff on small/medium systems. Since I can run
multiple independent simulations on different sections of the colvar
space, parallelization is not a problem.
I'd also like to run some ABF MD in larger membrane systems in the near
future, but if the system will be too large I'll rather apply for CPU time

> and how much time are you or your sysadmin(s) willing to spend
> on maintaining the machines and how much expertise is available
> to pick and choose the right hardware and not get talked into buying
> useless crap (as it happens far too often these days).

Again it's mostly just me:)

> the answer to each of these topics can have an impact as to which is
> better for you. buying machines with a "gamer" mainboard and 3 GeForce
> GPUs per machine is likely to give you the most bang for the buck, but
> if you don't have much technical experience then you may not be able to
> find the little details that are important to make them work well.

Yes, that might be the case as I don't (yet) have much experience with GPU

I'll probably go for two 32 core nodes and fill the rest with gaming boards
+ GPUs...

> SPEC benchmarks are useless, they are a tool to sell people
> what sales reps make a good commission on.

Why are they useless? I was so happy when I found out that the SPEC CPU2006
has a namd module.

Thank you for the answers,

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