Today's high-powered grahpics cards require a considerable amount of power to function - But all of this is about to change - From considerable to rediculous. ;)

ATI and nVidia's next gen cards will require not only one Molex® power cable, but two...

nVidia even warns that using two connections from the same power rail may cause major PSU problems!

http://theinquirer.net/?article=15246