"invalid device ordinal" on GTX 590

Hi,
I have replaced my previous Quadro Fx 380 card with a Geforce GTX 590 card. I removed the previous driver and installed the recommended driver “NVIDIA-Linux-x86_64-280.13.run” successfully.
I then installed Cuda toolkit 4.0 and the SDK.

My graphic card works fine with X11. However, I cannot access the card for GPU computation purposes.
Running the deviceQuery in SDK returns
:


[deviceQuery] starting…
./deviceQuery Starting…

CUDA Device Query (Runtime API) version (CUDART static linking)

cudaGetDeviceCount returned 10
-> invalid device ordinal
[deviceQuery] test results…
FAILED

Press ENTER to exit…

I tried installing older drivers, but had the same problem with versions 275-21 and 275-19.
In the system setting, my linux can only detect one GPU, but I believe it should detect 2, because the GTX 590 has two GPUs.

The driver status is as follows (by running cat /proc/driver/nvidia/gpus/(0 or 1)/information

GPU0

Model: GeForce GTX 590
IRQ: 16
Video BIOS: ??.??.??.??.??
Card Type: PCI-E
DMA Size: 40 bits
DMA Mask: 0xffffffffff
Bus Location: 0000:04.00.0

GPU 1

Model: GeForce GTX 590
IRQ: 18
Video BIOS: 70.10.37.00.91
Card Type: PCI-E
DMA Size: 40 bits
DMA Mask: 0xffffffffff
Bus Location: 0000:05.00.0

Please help me solve this problem.

My system info is as follows
Processor : Intel Xeon X5550 @ 2.67 GHz x 16
Graphics : GeForce GTX 590
OS : Fedora 15 (64bit)