no CUDA-capable device is detected (card installed and seen by the computer)

I have a GeForce GTX 560 Ti which is not used by the X server (it is a secondary card). I installed the GPU SDK, compiled the examples. For some reason, the card is not seen by the CUDA runtime (it is not seen by the OpenCL runtime either), so I get errors:

$ export LD_LIBRARY_PATH=/usr/local/cuda/lib64

/opt/nVidia-GPU-computing-SDK/CUDALibraries/bin/linux/release$ ./conjugateGradientPrecond

[conjugateGradientPrecond] starting...

../../common/inc/cutil_inline_runtime.h(398) : cudaSafeCallNoSync() Runtime API error : no CUDA-capable device is detected.

Other hardware information (the ATI card drives the display):

# lspci | grep VGA

01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Cayman XT [Radeon HD 6970]

02:00.0 VGA compatible controller: NVIDIA Corporation GF110 [GeForce GTX 560 Ti] (rev a1)

Reloading the nvidia kernel module driver (ver 295.20)

# rmmod nvidia

# modprobe nvidia_current

# dmesg | tail

...

[ 1277.382344] nvidia 0000:02:00.0: PCI INT A disabled

[ 1280.539164] nvidia 0000:02:00.0: PCI INT A -> GSI 40 (level, low) -> IRQ 40

[ 1280.539178] nvidia 0000:02:00.0: setting latency timer to 64

[ 1280.539188] vgaarb: device changed decodes: PCI:0000:02:00.0,olddecodes=none,decodes=none:owns=none

[ 1280.539390] NVRM: loading NVIDIA UNIX x86_64 Kernel Module  295.20  Mon Feb  6 21:07:30 PST 2012

# uname -a

Linux flair 3.2.0-18-generic #29-Ubuntu SMP Fri Mar 9 21:36:08 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

Any hint?

Sorry, I found now I have to create /dev/ nodes when the Xserver does not do it for me: http://forums.nvidia.com/index.php?showtopic=171168