Elite Bastards has posted a review on the Club 3D ATI Radeon X800RX 256MB video card

To put it simply, the Radeon X800RX is a Radeon X800GT, simply using a different name as decided by Club 3D. The clock speeds and architecture are the same as that seen in our recent Powercolor Radeon X800GT review, featuring as it does six vertex shaders and eight pixel pipelines clocked at 475MHz core and 490MHz DDR RAM (980MHZ effective). It does appear (from the part description on Club 3D's web site) that the Radeon X800RX uses only R480 cores, compared to Radeon X800GT parts which can be made up of either R423, R430 or R480 cores.

Club 3D ATI Radeon X800RX 256MB Review