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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

Before we discuss the results, we’d want to add a few words about the temperature factor. The temperature of the platters is what the service life of the platters and the accuracy of reading data depends on. But how can it be measured? If we measure it physically, with an external thermocouple, there is a question of the specific location. The top, bottom and side panels of the case and the PCB with the electronics can be used as such a location but it may be the top panel that is the hottest spot of one HDD whereas another HDD will be the hottest at its PCB. Measuring in multiple locations will produce a lot of numbers but won’t answer the question, what drive is hotter and needs more cooling.

Alternately, we could measure the temperature with the software, using the integrated thermal sensors. However, we can’t be sure about the accuracy of the sensor (every hardware tester is somewhat cautious about data offered by the manufacturer) and these sensors may be located at various places in the HDD. One maker measures the temperature of the heads, another measures the temperature of the platters, and a third maker will install the sensor into the electronics. How can such different data be compared?

Therefore we offer you the simplest method. According to the laws of physics, all the energy consumed by the HDD transforms into heat and is dissipated in the air. It may transform into heat in the chips, in the motor, in the heads actuator, but it is heat anyway. Thus, you can learn what HDD is hotter by comparing power consumption. Of course, the resulting temperature of the HDD and its components depends on cooling, but cooling is the responsibility of the end user. Our tests will show you how much heat must be dissipated from each specific HDD model.

Unfortunately, we don’t have the results for the Seagate Barracuda ES.2 but we suppose they are going to be similar to those of the Seagate 7200.11 because the electronical and mechanical sections of the two models are in fact identical.

Seagate’s previous-generation models and the economical WD7500AYPS prove to consume the most from the 12V rail. The updated version of Western Digital’s drive consumes less. The Samsung needs far less power than the others. Most of the drives have the same consumption from the 5V rail, which powers the electronics, but the Hitachi consumes about 50% more than the others.

Take note that this test shows the maximum currents. The overall consumption of each drive is changing in a complex manner and each drive takes a different amount of time to start up. Therefore you can’t measure the output power basing on these numbers.

Both RE2-GP drives from Western Digital are in the lead in idle mode: their reduced spindle rotation speed helped reduce the consumption on the 12V line. The updated WD7501AYPS is just brilliant as it needs little power from both 12V and 5V lines. As a result, it consumes 1.5 times less than its series mate and 2-2.5 times less then the 7200rpm models in idle mode. The Samsung and the new Seagate 7200.11 are the best among the fast drives: their electronics and mechanical parts both consume less power than in the other drives.

Random reading is the most power-consuming mode. There is nothing to optimize: the heads are moving wildly on the platters. It is clear that the Hitachi and the previous-generation drives from Seagate (which have almost identical results) are on the losing side. It is the mechanical components that consume the most, but the Hitachi also has voracious electronics. The two drives from Western Digital with a reduced spindle rotation speed are in the lead. The others are similar, with a total consumption of almost 11W.

The deferred writing optimizations help reduce power consumption in the random write mode. Of course, we have the same winners, but they consume more from the 5V line than the Seagate 7200.11 and the Samsung do. The latter are the best among the desktop drives: the new generation features not only the highest-capacity platters and better speed but also very economical components. The Hitachi and the Seagate ES are the worst drives in this test, consuming a lot from the 12V line.

The heads do not move much at sequential reading and the consumption on the 12V line drops down. As a result, the economical RE2-GP drives from Western Digital consume almost the same amount of power from the 12V and 5V lines. On the whole, we’ve got the same leaders and losers, but note that the consumption of the electronics from the 5V line contributes a lot to the overall result.

It’s the same thing with writing. Although the standings do not change, the Seagate 7200.11 and Samsung are very close to the economical models from Western Digital thanks to their low consumption on the 5V line.

 
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