The Caviar GP (for "Green Power") is the first 1TB hard drive to have variable rotational speed, ranging from 5400 rpm to 7200 rpm; Western Digital credits that technological change with helping the hard drive reduce its power consumption.

Though the Caviar GP isn't the fastest drive we've seen, it ranked fifth in performance, landing in the top third of drives we've tested. The Seagate 1TB drive, meanwhile, ranked third in performance. (For more information, see our full Top 10 Internal Hard Drives chart.)

The Caviar GP performed poorly on our file-seek tests, scoring in the bottom third of our field. On the other hand, it excelled on some of our read tests, posting the second-fastest time on our ACDSee test of performance on imaging tasks. And its performance on our WinZip file-compression test was better than average. "Better than average" describes the Caviar GP's results on our write tests as well.

By comparison, the Seagate Barracuda drive was the fastest on our write tests, outperforming the Caviar GP by 6 percent on our files and folders write test, and by 22 percent on our files and folders copy test. It was one of the slower drives on our read tests, however.

Power Savings, Too

We also ran the two drives through system power tests. With each drive installed, we measured the watts that our test system consumed in its off, sleep, and idle states.

During the off state and the sleep state, our system drew the exact same amount of power whether the Western Digital Caviar GP or the Seagate Barracuda was installed. Where we saw a difference, albeit a slight one, was when the system was idle. In that case, we observed a 3.2 percent drop in the power draw when we used the Western Digital drive instead of the Seagate.

Note that our tests show only the overall power draw, not the individual power draw of components such as the hard drive. Western Digital claims that the Caviar GP drops its operational draw to 8 watts, down from the 13 watts consumed by a previous-generation model. The company also says the power-consumption savings can reach up to 38 percent over a previous-generation drive. We were not able to test these claims.

You can conserve a little power with the Western Digital Caviar GP, which costs less than the Seagate--proving that going green can save a bit of green too.