Depending on which page you're looking at, Asus' website says the A7V133 supports Durons/Tbirds from 550MHz-1GHz or 550MHz-1GHz+. If you check through the various pages, you'll find it has a 133MHz FSB and has a maximum 12.5x multiplier, so the fastest speed it supports is 1666.667MHz (and that's without overclocking the FSB). It'll handle the 1.3GHz Tbird fine.