"RV770 certainly packs plenty into that transistor count, with a full core sporting a massive 800 Stream Processors to handle and process vertex, pixel and geometry shader data, arranged as arrays of sixteen units (or SIMD cores), of which there are ten. The cut-down version of RV770 used in the Radeon HD 4830 has two of these SIMD cores disabled, giving a total of 640 Stream Processors for it to play with, together with eight dedicated texturing units.

The Radeon HD 4830 features that cut-down RV770 core we mentioned with a couple of SIMD cores disabled, as well as clock speeds lower than the higher priced Radeon HD 4850, which sees it utilising a GPU core clock of 575MHz, with the 512MB of GDDR3 memory on-board clocked at 900MHz (1800MHz effective)."