The system as is needs 500w. The power supply i got was a 750w, Its not the silver like it states on the list. I actually got the gold. Its 5 star rated with great reviews. I think it will be fine. No I dont live near Micro Center. The Mobo was actually cheaper then the Extreme 4.
750W is enough for 2 7970s. There's still some headroom left afterwards. Plus, you're forgetting that most reviewers measured the power consumption which are power drawn from the wall (AC power), not really how much the system needs (DC power).