How do I enable ATI GPU under Windows(XP32) without connecting it to monitor?

Question

I have one monitor and 3 graphic cards installed. I need to enable all of the graphic cards for opencl (gpu-based) computations.

Answer 1

I'm not sure yet if there is a software method to do this (it could be a driver/OS limitation), but you can trick the GPUs into thinking they are active (without having a real monitor attached), by using a dummy VGA dongle.

See the first page of Google results for dummy vga for guides on how to do this (you might have to spend a couple of dollars on parts)

Answer 2

Right Click Desktop > Go to Screen Resolution > Click Detect Displays this will provide all the Inputs you have available on your system. There should be an option to connect the Input with VGA (Virtualised) this will then have it on your system as if it is plugged in to an output.

Can I also ask why you need three GPUs for computations, I'm pretty sure 2 will be more than enough, especially if it's one of the latest 5000/6000 series Cards.