NAMD CUDA on dual Nvidia 295 GPUs

From: David Chalmers (
Date: Thu Jul 23 2009 - 07:20:34 CDT

Dear All,

We are trying out the CUDA version of NAMD (2.7b1 CVS version from a few
days ago) on a machine with a quad core i7 cpu and two Geforce 295 GPUs. We
are using Suse 11.1 with the most recent NVIDIA drivers and cuda toolkit

We are seeing a speed-up in NAMD running on a single core, but as far as we
can tell, the speed up is only consistent with a single GPU being used.
When we use the 'nvidia-settings' gui, the temperature of only one of the
four GPUs is rising much.

This leads me to a few questions:

Can I use all four GPUs?

Should I be using one, four (or some other number) of cores?

Which version of NAMD should I be using, multicore or the charmrun version?

Is there some way that I can better understand how many GPUs NAMD is using?

Thanks for any advice,


David Chalmers
Faculty of Pharmacy, Monash University
381 Royal Pde, Parkville, Vic 3053. Australia

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