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Power Consumption

You can refer to our Hard Disk Drive Power Consumption Measurements: X-bit’s Methodology Indepth for details on this test. We’ll just list the specific modes we measure the power consumption in:

  • Start (the current the drive consumes when speeding up its spindle)
  • Idle (the drive is not accessed at all, but it is turned on and ready to work)
  • Random Read and Write
  • Sequential Read and Write

Let’s check out each mode one by one. We are especially interested in how economical the WD Caviar Green is in comparison with the other HDDs.

Well, the Caviar Green is indeed different from the others even during startup. Its electronics consumes about the same amount of power (the 5V line) as those of the opponent drives, but its mechanism needs but half the current required by the other HDDs among which the Samsung is the best. The Seagate shows itself as the most power-demanding device.

The WD Caviar Green is about twice more economical than the other HDDs. Besides consuming less power to rotate the spindle, which might be expected, it also boasts the lowest consumption of the electronics. As a result, it only consumes half as much as the other HDDs. According to the laws of physics, it dissipates two times less heat and has lower cooling requirements.

There are two leaders among the ordinary HDDs: the Samsung has the lowest consumption of the electronics (which is still 0.5W higher than that of the Caviar Green) whereas the Seagate preferred to economize on the 12V line, i.e. on the mechanics. The Western Digital Caviar Black needs the most power of all – it seems to be always ready for work.

There is nothing to economize or optimize at random reading. This is the most power-consuming mode of operation. The drives have almost the same consumption of the electronics except that the Seagate 7200.11 has a lower consumption on the 5V line than the WD Caviar Green. We’d applaud it if it were not for the poor performance of the Seagate when reading small data blocks. We don’t think it is worth the minor power-related benefits. Moreover, the Seagate eats so much power from the 12V line that its combined power consumption is higher than that of every other HDD. As for the economical WD Caviar Green, it is not as good in this mode as when idle, yet requires far less power than the 7200rpm models.

Deferred writing helps every drive to lower the power consumption at random writing in comparison with random reading. The Seagate has a much lower consumption on the 12V line and lowers its 5V consumption, too. As a result, it is very close to the leader Caviar Green. The latter is still unrivalled in terms of 12V consumption but its electronics are hardly economical, requiring just a little less power than the other drives from WD but more than the Seagate or Samsung. The Western Digital Caviar Black is the most voracious drive under this load.

>From a power consumption standpoint, sequential reading is better than random reading because the HDDs do not have to move their heads much. The 12V consumption is lower as the consequence. The electronics requires more power, however, because it has to process more requests.

It is the Seagate that has the most economical mechanics among the 7200rpm models in this test. The HDDs from Western Digital are hungrier, especially the Dual-Processor Caviar Black. However, it is the Samsung that is the worst drive in this test. Its electronics consumes 0.5W more than that of any other drive, and its mechanics is not quite economical, either. No drive can challenge the Western Digital Caviar Green which has more economical electronics and, especially, mechanics.

And finally, we’ve got sequential writing.

Western Digital’s drives, including the Caviar Green, have higher 5V consumption than the others. Coupled with the voracious mechanics, this makes the Black model the loser of this test. The Seagate is the most economical among the ordinary drives but it is still no match to the Green model from Western Digital in terms of combined power consumption.

 
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