as mentioned you must have an nvidia display card along with Tesla under WindowsXP and that NVIDIA display device must have an active display.
Chris, first run the NVIDIA control panel (right-click on the desktop) and tell us what you get when you select Help->System Information.
This should list your NVIDIA display card and the C870(s).
For example, my system reports:
GeForce 8800 GT
You can click on both of them and it should report ForceWare version 169.21 (from the brand new driver that added C870 support last week, that’s what I’m running in this configuration, I’ve also tried it with the D870).
If you don’t see both of these, let’s go back a few steps.
I’d try just running CUDA with your GeForce card alone. If deviceQuery doesn’t work with that, there’s still a more basic problem.
Make sure you’ve also got just the CUDA v1.1 toolkit and SDK, nothing from CUDA 1.0. And try just using the prebuilt binaries in the NVIDIA CUDA SDK\bin\win32\Release
I’m also still a little concerned Chris about your x4 electrical slots. I’m just not sure we’ve tried that with a C870 card - could be a power problem with those to the card? If you have a full x16 electrical slot you might want to try that first as well.
Also look at the windows hardware device manager. Under Display adapters you should see both your GeForce display card and the C870(s). Again, in my configuration it’s simular to what I show above from the NVIDIA Control Panel, both the GeForce 8800 GT and Teslsa C870 are listed
Please let us know what these report.