GPU-based video cards to accelerate your program calculations, How?
I imagine that they are using a language like CUDA to program the critical sections of code on the GPUs to accelerate their computation.
The main function for the program (and its threads) would still run on the host CPU, but data are shipped off the the GPUs for processing of advanced algorithms. CUDA is an extension to C syntax, so it makes it easier to programmer than having to learn the older shader languages like Cg for programming general purpose calculations on a GPU.
A good place to start - GPGPU
Also, for the record, I don't think there is such a thing as non-GPU based graphic cards. GPU stands for graphics processing unit which is by definition the heart of a graphics card.