Just like to take the time and warn people about asus's latest bios, whatever you do don't update your bios to 1602 otherwise you'll regret it. What it does is downgrade your processor so that its running at 800mhz (200x4) has a noticeable effect on general system performance as well as gaming. Applies to all x4 users its some kind of bug they introduced when improving compatibility with the latest x6 processors. EZflash won't let you downgrade but there is a solution check the link below for more information.
It is important to list your Motherboard model as the bios would only apply to one board.
Its also of note that your problem likely isn't an issue with all X4. It looks like the people having this issue so far were using X4 965 with C3 stepping. It is likely a problem with that cpu only or perhaps all C3 steppings.
Yeah your right my motherboard is an AM3 Crosshair III, not just people with 965 chips, 955 chips have also been affected by the bios update. Anyway all i want to do is warn people before they do the same thing. Mine's fine now ive downgraded the bios following the guide in the link. Least now i can play some games without worrying about my processor.