The RV635 and RV620 are upgrade versions of the Radeon HD 2400 (R630) and 2600 (R610). The new chips will adopt a 55nm process, compared to 65nm of the previous chips, and will have core frequencies increased to 800MHz, noted the sources.
The RV635 and RV620's main upgrade comes from their DirectX 10.1 compatibility, making the chips Shader Model 4.1 compliant. Both new parts will be PCI Express 2.0 and Display Port compatible. AMD schedules to provide samples of the new chips to manufacturers in October this year, while the first graphics cards using the new parts should start rolling out in January 2008, in both XT and Pro variants.