I have the same mobo, power supply, and video card you do as
well as the same shutdown problem.
The problem is your power supply. The Thermaltake 480W is
not ATX 2.0 compliant. If you go to their website it is listed
as a ATX 1.3 power supply.
You need to get a 2.0 compliant supply. I have a PC Power and
Cooling 510 and no longer get the shutdown problem when I
launch my games. I've heard of others with success with the
Antec 480W.
These threads may help you as they helped me.
http://www.houseofhelp.com/forums/sh...1&page=4&pp=30
http://houseofhelp.com/v3/showthread.php?t=33162