Newbie question about number of CL devices

I’m just starting to learn OpenCL. My development machine has three Evga 8800GT cards, not in SLI.

When I run GPU Caps, the first tab says:
Main video card - SLI disabled - 3 GPUs

But on the OpenCL tab it says
Number of CL devices: 2

The CUDA tab also says
Number of CUDA devices: 2

In Device Manager, all three cards are installed and working properly.

Why doesn’t GPU Caps report three cards?