[gmx-users] problems for GPU simulations

[Albert]

Hello:

  I got a workstation with two GTX590 which have two core for each GPU. 
I can submit gromacs GPU jobs with command:

mpirun  -np 4 mdrun .....

with such running, I can get 26ns/day for Gromacs-4.6 beta version.

However, I found that for Gromacs-4.6 final version (which is the latest 
one), it claimed that I only have two GPU, it asked me to adjust -np to 2.

so I submit the jobs with command:

mpirun -np 2 mdrun...

for the same system with the same paramters (of course the tpr file must 
be regenerated). I found that I can get only half of the speed, 
something around 10 ns/day.


So I am just wondering what's happening?

thank you very much
best
Albert