To test power consumption today we are using a Keithley Integra unit and we measure power consumption from the VGA card inputs, not the system wide drain. We measure results while gaming in Crysis 2 and record the results.
The Sparkle GTX650 OC Dragon Series is an extremely efficient discrete solution, only demanding around 40W of power when gaming. This really is ideal for a media center environment or when building into a space restrictive chassis.