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 Warhead and record the results.
Nvidia's power modifications to the GF104 transistor layout are noticeable, although the GTX460 wasn't that bad a design either on reflection. These are really almost identical to the XFX HD6950 XXX edition we tested a short while ago.