I saw this a while ago, might be old news, but the good guys at ASUS have released BIOS updates that allow you to unlock the clock multiplier on their boards. This isn't just for their new boards, they are doing this for boards that go as far back as the P4P800 (and a couple of earlier ones).
http://au.asus.com/news/2004/20040921.htm
http://au.asus.com/news/2004/20040921.htm