"PowerVR have designed their own similar variation of 3DFX's Hidden Surface Removal. This technology was implemented on the original Kyro and is called Tile-Based Rendering. Memory bandwidth is one of the biggest bottlenecks in graphics cards today and tile-based rendering effectively uses available memory bandwidth making it less of a bottleneck. What Tile-based rendering does is, instead of rendering every pixel whether it is visible or not, it only textures visible pixels. Groups of polygons are batched together (in "display lists") before being processed by 3D hardware. This allows the scene to be grouped into smaller 32x16 tiles which are then rendered independently. This in turn eliminates the need for frequent access to external memory."
FULL STORY @ ACIDHARDWARE (http://www.acidhardware.com/reviews/3dprophet4500/index.shtml)