Have you tried just running one instance of WoW?

Pull a stick of RAM and run one instance, testing to see if without a particular stick your computer doesn't BSD?

Have you defragged?

Checked to make sure all fans are working, especially CPU and GPU fans?

Made sure the video card isn't dirty?

Try running in non-windowed mode?

Is it exactly after 10 minutes, or could a particular location/action in game be the pattern?