Noise levels
Noise levels were measured with an Extech 407727 Digital Sound Level meter 1" from the side of the drives at idle and under an HD Tach seek load. Drives were run with the PCB facing up.

Thus far, we've seen the Caviar GP's performance suffer due to the drive's slower spindle speed, but here's where it all starts to make sense. The GreenPower is the quietest desktop drive we've ever tested, by close to a decibel and a half at idle. When seeking, the GP is more than two decibels quieter than the next closest high-capacity drive. What's more, it's a whopping six decibels quieter than a Deskstar with equivalent capacity.

Power consumption
For our power consumption tests, we measured the voltage drop across a 0.1-ohm resistor placed in line with the 5V and 12V lines connected to each drive. Through the magic of Ohm's Law, we were able to calculate the power draw from each voltage rail and add them together for the total power draw of the drive.

The Caviar GP delivers on its energy efficiency promise, too. Even with a terabyte spread over four platters, the drive consumes less power than a single-platter, 160GB Barracuda 7200.9. At idle, you save about three watts over a Deskstar 7K1000. Under a seek load, that advantage grows closer to eight watts, with the Caviar GP pulling half the power of the 7K1000.