[gmx-users] why two GTX780ti is slower?

Albert mailmd2011 at gmail.com
Wed May 14 07:03:27 CEST 2014


I've compiled Gromacs in a GPU machine with two GTX780Ti with following 

env CC=icc F77=ifort CXX=icpc 
<> cmake .. 

I've got 40ns/day for a 65,000 atoms membrane system under CHARMM36 FF 
when one GPU is used, but it is only 27ns/day if I used two GPUs. In 
another machine with two GTX690, I used ICC+openmpi instead of ICC+intel 
MPI. The same system, I obtained 40ns/day for one GPU, and 60ns/day for 
two GPU.

I am just wondering, why it is even slower with two GTX780Ti for my 
system, which doesn't happen to GTX690?

thx a lot


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