R481 is a R480, for the Radeon X850 with an AGP interface. ATI won't bridge this chipm it will make it native as ATI decided to do native chips as long as it makes sense to do so. We heard this from the ATI CEO back at Computex 2004.More info about the R481 at The Inquirer
ATI to launch another high-end AGP card - the R481

The Inq reports that ATI has decided to make one more high-end AGP chipset, the R481. It's basically the same as the R480, but with an AGP interface.