Hmm....there really isn't a set speed. Some people got 1 GHz TBirds running, some can't even get 700 MHz. I couldn't get it to work with an 800 myself. I ended up exchanging the board for a K7M, which has worked flawlessly. The only like performance differences between the boards are AGP 4x and 133 MHz RAM. So you might as well try it out, and if it doesn't work out, just exchange for the K7M.