Power Consumption

You can refer to our article called 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 drives are in comparison with the others.

Let’s turn them on now.

We’ve got three leaders in terms of 12V consumption. And while we could expect the 3-platter WD Caviar Green drives to be in the lead (they have three platters to spin up to only 5400rpm), it is quite a surprise to see the Seagate SV35.3 in third position. Perhaps it just starts up the way it words, i.e. very slowly, and does not require high current for that. Next go a group of medium-consumption devices. As for the losers, they are all of the 4-platter drives (save for the SV35.3), the WD RE3 and the 3-platter Seagate 7200.11. The latter two drives must have required more power in order to get ready to work in the shortest time possible.

As for 5V consumption, we have a large group of medium-consumption drives, too. The two new drives from Hitachi can be singled out among them thanks to their new electronics. The older Hitachi is the most voracious model in this test. The 4-platter Green drives from WD need rather too much power from the 5V line but their 3-platter mates are less hungry because Western Digital promptly replaced their electronics.

Well, it is hard to question the power efficiency of Western Digital’s Green products. Their 12V consumption is only half that of the other drives. Their electronics (the 5V line) has a modest appetite, too. Only Hitachi’s new models can compare with the Green series in this respect. By the way, Hitachi’s new drives are also very economical in comparison with their predecessor 7K1000 in terms of 5V consumption. Samsung’s HDDs have economical electronics, too.

When the drive is not accessed, its mechanics just keeps the platters rotating. The 3-platter models are unrivalled here: the older drives consume noticeably more. The only exceptions are the Hitachi 7K1000.B that has surprisingly high power consumption and the Seagate SV35.3 which proves to be economical.

When it comes to WD’s Green series, the reduction of platters from 4 to 3 helped lower their power draw by half a watt. This is a difference considering that the total power draw is below 4W.

And of course the Green drives have no rivals in total consumption. The Hitachi E7K1000 is the most economical model among the 7200rpm drives while the earliest 1-terabyte models, the Hitachi 7K1000 and the 4-platter Seagate 7200.11, have the highest power consumption.

Random reading is the most power-consuming mode because the HDD cannot save power. It has to move the heads about at maximum speed, looking for necessary tracks. The electronics can work not at its full capacity, however, because there is no stream of accesses to buffer memory here.

Hitachi’s new models must be noted. The old 7K1000 looks like a voracious monster while the new models are much more modest. Their electronics is very economical again while the mechanics is still demanding, even though being 2W more economical than the mechanics of the ten-headed ancestor.

It is no wonder that WD’s Caviar Green and RE2-GP drives are the best ones in this test. Interestingly, the 4-platter Green models are not much better than the 7200rpm drives whereas the 3-platter models are 50% better due to the 0.5W reduction of the power consumption of their mechanics (thanks to the lack of one platter) and the same reduction in the consumption of their new electronics. The model with 32GB buffer is especially impressive now. Its performance is just brilliant when you know that it consumes so little power.

The SV35.3 is the best 7200rpm drive, but we don’t think this is a good price for its low performance. Perhaps Seagate should have released the drive with a lower spindle rotation speed, like in WD’s products.

Deferred write algorithms came into play at random writing, and the HDD’s heads do not have to move about so quickly. But the HDD has to access its buffer memory a lot.

Western Digital’s Green drives are still in the lead thanks to their low 12V consumption but the new models’ electronics is not the most economical. The older models’ electronics is almost the most voracious among all the drives. As a result, the old 4-platter WD Caviar Green and RE2-GP consume as much power as the 3-platter Seagate (its electronics proves to be economical here). Every drive from WD has higher consumption than same-class drives from other brands – this must be the tradeoff of their effective firmware algorithms.

The Hitachi 7K1000 is the obvious loser here. It consumes very much from both 5V and 12V lines and its total power draw is 50% higher than that of any other HDD.

The HDD’s electronics contributes more to its power consumption at sequential reading because the heads only have to stay above the track.

The 3-platter 5400rpm drives are still in the lead while their 4-platter predecessors are not that good. They have low 12V consumption but consume a lot from the 5V line. As a result, Hitachi’s new drives catch up with them, showing very economical electronics. WD’s 7200rpm drives look good, too. The RE3 and Caviar Black are only 0.5W slower than Hitachi’s products and are almost as good as the RE2-GP.

The losers are the 4-platter Seagate 7200.11, Samsung F1 DT and Hitachi 7K1000. They have the highest 12V consumption, and the old Hitachi also has the most voracious electronics.

The standings are overall the same at sequential writing but Western Digital’s drives, save for the 3-platter Caviar Green, have lower places. The 5400rpm drives consume as much (or even more) power from the 5V line as from the 12V line. That’s the tradeoff of efficient caching algorithms at a reduced spindle rotation speed.

Summing up this section of the review, we’d like to note the results of the new drives from Hitachi. Their new electronics is very power efficient, and their mechanics has become more economical, too. It’s time for the 5-platter ancestor to retire now.