read review here
"VIA released another "new" Socket462 chipset to the market, the KT-400. People are asking, what are the improvements over KT-333? The answer? Not many, I am afraid. The memory controller is left untouched thus do not expect a "huge" increase in performance when running at the same FSB and memory ratio. The new features are: AGP 8X support, increased bandwidth between the north and south bridges, and unofficial DDR-400 support. The unofficial support for DDR-400 really makes you wonder why they name it as KT-400? I personally think the DDR-400 is a temporary solution and maybe superseded by KT-400A or KT-466 with unofficial support for DDR-466. Anyway, enough rants on KT-400, let get on with the Gigabyte's KT-400 offering, 7VAXP."