Hard Disks and Solid State Drives

Test Setup

• Intel Core i7 870
  
• Asus Maximus III Extreme (P55, 0309 BIOS)
  
• 4GB OCZ DDR3 PC3-15000 / 1,866MHz / Platinum Edition @ SPD: 1,333MHz, CL7
  
• 650W Seasonic X-Series PSU
  
• ATI Radeon HD 5770 1GB
  
• ATI Catalyst 10.1 WHQL
  
• Windows 7 Home Premium x64

Quite often we've heard from storage manufacturers who claim their low power "green" drives will save on carbon footprint or that SSDs require next to no power because they have no moving parts.

We decided to put this to the test test with a small roundup of drives: 'performance' 7,200RPM, 'eco' 5,400 - 5,900RPM hard disks, with varying platter quantities, as well as an Indilinx-based SSD. We measured the power at the wall socket when the system and drive was idle, and then when the drive was being written to with a few hundred GB of mixed file sizes. Unfortunately recording the exact power consumption is difficult because we have to copy from one drive to another, so inevitably, the results include include the read-power use of our reference disk. It also doesn't take into account the power use at initial spin-up of the mechanical disks, which is considerably greater but for a very short time.



The power difference between the 5,400 - 5,900RPM and 7,200RPM drives appears to be between 3 - 5W, depending on the number of platters and which brand you buy. Even with a full complement of six disks (i.e. filling up all the SATA ports on a typical motherboard), that's an 18 - 30W saving: not that much for six of anything, but obviously notable if you're building a ~50W server or home theatre, which is one of the few situations we'd promote using the green drives for.

Surprisingly, the SSD doesn't save us that much power either - just 2 - 3W again on top of the 5,400 - 5,900RPM drives at idle and when writing, however compared to the performance drives from Seagate and Western Digital the difference is a more considerable 7W per drive. You're unlikely to have many SSDs unless you’re in enterprise storage, where 7W a pop (or more for 10 - 15k SAS drives) means power savings abound.