The graphical processing units (GPUs), made by Nvidia and ATI, function as components in graphics subsystems that power everything from Microsoft's Xbox to high-end visualization systems from Hewlett-Packard and SGI. The GPUs act as coprocessors to CPUs such as Intel's Pentium, using a fast bus such as Intel's Advanced Graphics Port. As such, the GPU is visually and visibly changing the course of general-purpose computing.