R9100其實就是當初的R8500。
且這三張都是完整支援DX8.1，而不支援DX9喔！！
引一段TOM的文章：
let's look at ATi's new entry-level chip. The Radeon 9200 VPU (RV280) is the replacement part for the Radeon 9000 series. This chip only differs from its predecessor in its AGP 8x support and its higher clock speeds. The core is still based on the Radeon 8500 design with its four pixel pipelines, but, like the 9000, it only has one texturing unit per pipe, instead of the 8500's two.

嚴格說起來應該是R8500（R9100）效能最好 ！