The video card hardware essentially contains the graphics
algorithms that were learned in the DOS days and even before
that. The algorithms are in the hardware and are extremely fast.
Rasterization, filtering, perspective correct texture mapping,
anti-aliasing, vertex shaders, pixel shaders, etc, are all done
on the GPU. You could never hope to achieve the effects and
quality of current games without having specialized hardware. It
is possible but not practical nor feasible. Anything done in
software can be done in hardware but the hardware will always be
faster. So the same paradigm exists between hardware and
software. Essentially anything done in hardware can be done in
software albeit a bit slower. The modern video card is probably
as complex as the CPU and I would guess it processes faster or
perhaps is more parallel in execution. Not to mention it does
not have to service the entire computer system nor perform any
interrupts, etc. So it has less to do and yet also has a bit
more to do than the CPU. A pi