I don't think so.. I don't own an X-Box (although a friend of mine does, maybe he'll let me take it apart) but I highly doubt it has any options to raise the FSB, for example. Besides, even if it could, and it would probably be located in the BIOS (shitty motherboards don't let you change anything -- not physiclly [jumpers] and not using a program [bios]), I don't think the virus could control that.
It could, though, fake a mesage telling the user to fix his x-box by rubbing his favorite magnet on the hard drive