You can refer to our article called Hard Disk Drive Power Consumption Measurements: X-bit’s Methodology in Depth for details on this test. We will just list the specific modes we measure the power consumption in:
- Start (the current the drive consumes when starting up)
- 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.
The HDDs split up into three groups in terms of startup current. As expected, the power-efficient products need less power although the Seagate Barracuda LP is an exception. Its startup power consumption is as high as that of the most voracious drives which include the two other drives from Seagate and the new WD Caviar Black series.
The WD Caviar Green behaves unnaturally in the idle mode. Its power consumption is too high and the oscillograms suggest that the HDD is not idle at all. We don’t know what this HDD was doing all the time but it did not get to sleep even after an hour of being in idle mode.
The other power-efficient HDDs are all right: they take top places, the Samsung being the most economical one in terms of 12V consumption.
Western Digital’s E3 has some mysterious activity on the 5V line, too. At the same time, it is phenomenally economical in terms of 12V consumption. Although we can see a general trend towards lower consumption from the 12V line with the WD products, the difference of 1.5 watts from the very similar Caviar Black FAEX is a serious one. We can only suspect that the HDD entered a very deep sleep mode, shutting down everything save for the platters drive.
The Hitachi is good. For all its 7200 RPM, it needs less than 5 watts when idle. Well, nearly every HDD deserves our praise here. For example, the Seagate Constellation ES consumes a mere 5.4 watts – a fantastic result compared with the first generation of 7200 RPM drives.
Random reading is when the HDD turns off its cache and moves its heads around. Therefore, the results differ only on the 12V line. The Samsung saves a lot of power, the WD Caviar Green following it closely. The Seagate Barracuda LP is, on the contrary, not very good, consuming almost as much as the 7200RPM Seagate Barracuda XT and WD Caviar Black E3. The 3-platter models consume more in the Caviar Black series. Quite expectedly, an HDD has to spend more power to rotate three rather than two platters.
The Hitachi leaves us perplexed. It has only two platters and its heads do not seem to be very quick, so what does it need so much power for?
Random writing is overall similar to random reading in terms of power consumption although each HDD consumes less power due to caching. The WD Caviar Black E3 is especially good, being almost as economical as the 2TB power-efficient models. The Seagate Barracuda XT is good, too, for an HDD with four platters rotating at 7200 RPM. It is the first-generation WD Caviar Black that consume the most power of all.
The Hitachi competes with the 5400RPM drives in terms of power consumption at sequential operations. And it does so successfully thanks to the low consumption on the 5V line. The WD Caviar Black E3 is far more economical than its predecessors as well as its cousin with 64MB buffer. The Seagate Barracuda XT is the most uneconomical drive here, although it differs but slightly from the 3-platter WD Caviar Black models.
Finally, we can note that modern HDDs all have a power consumption of 10 watts and lower. The reduction of spindle speed produces a 25% reduction in power consumption (and, accordingly, heat dissipation).