ATI's Radeon X800 256MB and Radeon X850 PRO -
They're effectively the same GPU, built on different process nodes at TSMC, ATI's discrete GPU fabricator. Both are natively PCI Express, both have four fragment quads (groups of four fragment units), a sextuplet of vertex units to feed them, a 256-bit wide memory bus and all the core R4xx series technologies that define ATI's latest parts. That includes support for anti-aliasing at ever higher resolutions, 16X angle-adaptive anisotropic texture filtering and bilinear texture samplers (one per fragment unit), to name just a few.