Momentus 5400.6 & Scorpio Blue: Seagate & WD 2.5" HDDs at 500GB

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March 2, 2009 by Mike Chin

Seagate Momentus 5400.6 500GB

WD Scorpio Blue 500GB
Market Price

In the 15 months since our last review of a 2.5" notebook drive, they more than doubled in capacity, dropped signicantly in price, and moved entirely to the SATA interface. Their use in small desktops is now much more common, so SPCR is no longer alone in encouraging such use. The era of nettops is on us, and 2.5" notebook drives are frequently used in place of standard 3.5" desktop drives for their smaller footprint and lower power/heat disspation. Since they are usually quieter than 3.5" desktop drives, this is a good trend for noise-conscious computer users (although as our review of the Dell Studio Hybrid mini PC showed, how a 2.5" drive is mounted in the chassis has a substantial impact on propagated noise).

The two 500GB 2.5" drives under review here are the current capacity flagships of the respective brands, Seagate and Western Digital. Samsung and Hitachi reached 500GB capacity a little sooner, but they did so with 3-platter designs. With Hitachi, this resulted a physically thicker 12.5mm drive rather than the standard 9.5mm. The latter dimension is necessary for a drive to fit into a standard notebook.

The half-terabyte capacity on the Seagate and WD drives is achieved with just two platters, so both drives adhere to the standard notebook drive form factor. The areal density is 394 GB per square inch, according to Seagate. Given the much smaller platter size, this is probably at least as high as the 375 GB/platter achieved in their 1.5 TB 4-platter 3.5" desktop 7200.11. Refinements in perpendicular recording helps achieve such high density. These 2-platter designs provide several advantages over the 3-platter competition:

  • Higher areal density means higher throughput speed.
  • Fewer platters means lower complexity and manufacturing cost.
  • Fewer platters also means lower power usage and cooler operation, especially important for battery-powered mobile devices.

We'll examine each drive in turn, then compare and contrast the two.


Seagate Momentus 5400.6 500GB (from Seagate's web page)
8-MB cache delivers fast performance. Does not seem so much for a 500GB drive.
SATA 3.0Gb/s interface with Native Command Queuing The highest SATA bus speed currently available, but NCQ is not really useful for desktop computing.
Up to 1000 Gs of Shock Resistance in non-operating mode Seems high, but it's not really. If the drive falls 1m and the impact lasts less than half a millsecond (quite plausible with a hard floor and rigid drive casing), then 1000G will be reached. (Thanks to Chris Friesen for this insight.)
Designed-in G-Force Protection technology for added durability and
reliability during accidental drops
Senses when the drive is in free-fall, moves heads off the platter and locks them in place within 0.3 second.
QuietStep™ technology enables ultra-quiet load/unload acoustics. Better than previous generation Seagate laptops?
Seagate laptop power management technology and ramp load features that remove the head from the disk
during idle to improving idle power consumption
OK, we'll measure and see if there's any change from previous drives.
5-year limited warranty Standard for Seagate packaged drives.


WD Scorpio Blue 500GB (from WD's web site)
Massive capacity No argument there.
Reliable and rugged - WD's ShockGuard™ protects drive mechanics and platter surfaces from shocks. SecurePark™ parks the heads off the disk during spin up, spin down, and when the drive is off. Sounds familiar, doesn't it?
Quiet - WhisperDrive™ combines state-of-the-art seeking algorithms to yield one of the quietest 2.5-inch hard drives on the market. These algorithms also optimize the way a drive seeks for data, which significantly improves power consumption. OK, we'll be testing for acoustics to verify.
Fast and efficient - 5400 RPM spin speed, 12 ms access time and up to 3 Gb/s SATA interface speed. OK
Tested for compatibility - We perform tests on hundreds of systems and a multitude of platforms in our FIT Lab™ and Mobile Compatibility Lab to give our customers confidence that our drives will work in their systems. Sounds good, but we'd expect all the drive makers to do the same, no?
3-year limited warranty Standard for WD Blue.


The specifications of the particular drives are compared below. There isn't a lot to differentiate them, and the most important parameters — transfer rate and acoustics — are cited differently, so a quick comparison is not simple. The difference in the acoustic specs are interesting. Bels, used by Seagate, is a measure of sound power. Decibels A-weighted (presumably at 1m distance) is a measure of sound pressure level. A sound that measures 2.4 bels generally measures considerably lower than 24 dBA@1m SPL, so the Seagate would appear to be quieter. One would not expect such differences from such similarly spec'd drives. We'll see from our own measurements soon enough.

Specifications: Momentus 5400.6 500GB & WD Scorpio Blue 500GB
(from their respective data sheets)
Seagate Momentus
WD Scorpio
500 GB
500 GB
8 MB
8 MB
Disks / Heads
2 / 4
SATA 3Gb/s
SATA 3Gb/s
Spindle Rotation Speed
5,400 RPM
5,400 RPM
5.6 ms
5.5 ms
Random read seek
14 ms
12 ms
Maximum Transfer Rate
Internal (Mb/s)
External (MB/s)

Host to/from drive:
106 MB/s (maximum)
98.8 g
117 g
Operating Temperature
0 - 60°C
0 - 60°C
Power Requirements (W):
Read / Write
Idle / Standby

2.6 / 2.85
0.8 / .23

0.85 / 0.25
Acoustics: Idle / Seek
2.4 / 2.6 Bel
24 / 26 dBA

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