[gmx-users] hardware problem of GPU?

[Albert]

Hello:

I've got a GPU machine with two GTX780 Ti card. Here is my configurations:


Intel Xeon E5-2690V2, 10 Cores, 3.0 GHz
Silent Cooling
ASUS P9X79 WS
32 GB ECC-DDR3-RAM 4-Kanal, 1600 MHz, 4 x 8 GB
250 GB Samsung 840 EVO SSD
4000 GB WD Harddisk, 7200 rpm
2 x ASUS Nvidia GeForce GTX780 TI 3GB GDDR5, SLI configuration
Samsung DVD Drive
Cardreader 40 in 1
Logitech Wireless Desktop MK270
CM Midi Tower Silencio 652, black
Matching low noise Power Supply
PCIe Card with additional 2 x USB 3.0


I noticed that the speed for 2GPU is slower than 1 GPU for several 
testing system (atom no. 10,000-60,000 under either Amber FF or CHARMM 
FF). So I am just wondering probably there is some problem for the GPUs 
connections? Does anybody have any idea how should I arrange the GPU so 
that the speed can be maximum?

thanks a lot

Albert