I have the following hw & sw configuration:
- [*]CPU Intel E8500 (2 cores @ 3.16 GHz and 6 MB cache)[*]8 GB DDR3 RAM @ 1333 MHz[*]Mobo Ultra 790i[*]3 graphics cards 9800 GX2 (1 EVGA overclocked by the manufacturer, 1 Nvidia, 1 XFX)[*]PSU Cooler Master Silent Pro Gold 1000 W[*]Windows 7 Ultimate 64 bit[*]CUDA toolkit 3.2[*]Driver Nvidia 266.58[*]Visual Studio 2008 with 64 bit support
Windows sees correctly 6 GPUs with the right driver. Nvidia system monitor shows the physical state of all the six GPUs. But if I try to launch a CUDA application from a command window to enumerate the GPUs I can see just a single GPU when the multi-GPU flag is disabled in the Nvidia performance monitor. When I enable the flag to a multi-gpu configuration, the card with the connected monitor configures to multi-GPU, CUDA works correctly and I can see 5 GPUs or 4 GPUs, apparently in a random way after the boot of the machine. Has anybody out there experienced such a behavior? Could there be an explanation or a possible correction to it to have all the GPUs at work with CUDA applications?