• Home
  • blog
  • Seagate Momentus 5400.2 120GB SATA notebook drive

Seagate Momentus 5400.2 120GB SATA notebook drive

blog image

This is a second generation sample of Seagate’s flagship model Momentus, now with SATA interface and the highest capacity of any 5400 RPM notebook drive. Our sample of one of the original Momentus left us nonplussed. This 5400.2 fares much better.

August 9, 2005 by Devon
with Mike


Seagate Momentus 5400.2 ST9120821AS
120GB, 5,400 RPM Notebook drive



Market Price

As a general rule, notebook drives tend to be significantly quieter than their
larger desktop cousins. Yes, they are a little slower and smaller, and they
cost more per gigabyte, but in terms of noise they are second to none. The light acoustic signature makes notebook drives desirable for the quietest desktop systems. It’s a discovery made by many SPCR readers.

Seagate is dominant among HDD makers, owning at least half of the global hard drive business. It created the first truly low noise 7200 RPM desktop drive in the Barracuda IV some four years ago. The B-IV was in another class for noise compared to other drives of its day, and it remains one of our reference quiet drives. Since then, Seagate’s position in HDD noise has been eroded, with no clear low-noise leaders among either desktop or notebook drives. Seagate introduced the Momentus notebook drives a year and a half ago, along with a commitment to make 2.5″ the top enterprise HDD form factor within a couple of years. This process is one we continue to watch.

Seagate’s entire notebook line is sold under the Momentus name, and includes
countless models of varying spindle speed, capacity, and interface. What
identifies a product are the numbers after the name. Our sample
is a 5400.2, indicating that it is a second generation 5,400 RPM Momentus. SPCR
reviewed one of the original 5,400 RPM Momentus drives when we asked Is
the Silent Future 2.5″ Wide?
over a year ago, and we were
disappointed to find that it produced a pure high pitched tone that was louder than our reference
desktop drives. However, several users in our forums have noted that newer drives
do not exhibit this sound, so we returned to the Momentus line with high hopes.

This Momentus 5400.2 sample has plenty to set it apart from its competitors. It is
one of the few SATA notebook drives on the market currently, only the second SATA notebook drive we’re examining, and its 120 GB capacity is a step above the competition. Even so, Seagate has
recently announced a third generation: The 5400.3 features Full Disc Encryption
as an added security measure against data theft. However, at the time of writing,
none of these have appeared in retail channels.

The Momentus 5400.2 120GB model.

SEAGATE MOMENTUS 5400.2 ST9120821AS (quoted from

SoftSonic FDB motor: Delivers inaudible operating acoustics

Inaudible is a bold claim, but not impossible for a notebook drive.
Just remember that “inaudible” is relative to ambient noise.

QuietStep ramp load technology: Enables whisper-quiet load/unload
and 900 G’s of non-operating shock tolerance

Loading and
unloading the heads often sounds like ordinary seek noise.
shock of 250 Gs
to withstand rugged notebook environment
to Seagate
: “An operating shock of 225 Gs is equivalent to
dropping a typical notebook computer approximately three inches flat onto
a concrete surface while it is running.”

8-Mbyte cache buffer: Optimizes performance so applications run
fast and smooth

8 MB is standard for notebook drives these days.

5400-RPM spin speed: Provides almost 50 percent more performance
for notebook computers while maintaining battery longevity

The 50%
figure is in relation to 4,200 RPM drives, which are starting to be discontinued.
Serial ATA
with Native Command Queuing
: Blazing fast 1.5Gb/s interface speed combined
with NCQ for high performance
SATA is very
convenient, especially for desktop users: No adapter is required to connect it to a
modern motherboard.


The specifications below are specific to model that we examined. Capacity,
cache size, platter number, interface, and even performance vary from model
to model even within a single product line. Acoustics and power dissipation
also vary depending on the number of platters in the drive; smaller capacity
drives tend to have fewer platters, and tend to produce less noise and use less

Specifications: Seagate Momentus 5400.2 ST9120821AS
120 GB
8 MB
Spindle Rotation Speed
5,400 RPM
SATA 1.5 Gb/s
5.6 ms
Average Seek
12.5 ms
Internal Transfer Rate
336 Mbits / second
0.1 kg
Operating Temperature
5 – 55°C
Power Dissipation: Idle / Seek
0.8 / 2.2 W
Acoustics (Idle)
2.4 Bels

The SATA interface has not yet become common for the notebook form
factor. Most notebooks use a version of the EIDE interface, and this
is reflected in the marketplace availability of SATA notebook drives. SATA is quite desirable as many desktop motherboards
ship with only a single IDE channel. Furthermore, SATA notebook drives do not
require an additional adapter to work properly in a desktop system.

It must be noted that SATA is set to sweep notebook drives, and all the brands will soon be avaible in SATA; it’s just a question of time. Notebook PC makers will adopt SATA as their exisiting supplies (and contracts for supplies) of components related to the previous IDE/ATA connector are depleted. These include not only the drives, but also notebook motherboards with native plug in ports for drives, and any other peripherals that may go into a notebook HDD interface.

Another step forward is the increased capacity. Although 120
GB is hardly large in desktop terms, it is 20 GB larger than almost every other
notebook drive on the market. The one exception, as far as we know, is the 120 GB Fujitsu MHV2120AT, which is a slower 4200 RPM drive. Every other 2.5″ mobile drive appears to be limited to 100 GB. Most users will probably stick to the lower capacity
models anyway, as the extra 20GB capacity isn’t enough to justify buying it for archival or
A/V purposes. On the other hand, the extra 20 GB may be useful to a user (like me) who chronically
runs out of space no matter how much storage there is.

Even if the extra capacity isn’t needed, it still has the ancillary benefit
of a small performance boost thanks to increased areal density. This benefit should apply to the
models that use 60 GB platters: The 120 GB, 60 GB, and 30 GB models. The other
capacity models in the 5400.2 line may not benefit, but it’s impossible
to say for certain without knowing how Seagate has manufactured them —
or by performance benchmarking the drive.

Keep in mind that this performance advantage over smaller drives is theoretical.
We do not have enough experience with the performance of current notebook drives
to say for certain how much the higher areal density benefits performance, nor
are we interested in doing serious performance benchmarking.


Our sample were tested according to our standard
hard drive testing methodology
. Our methodology focuses specifically on
HDD noise, and great effort is taken to ensure it is comprehensively measured
and described. Performance is not tested, for reasons discussed in detail in
the methodology article. For comprehensive HDD performance testing results,
we recommend Storage
, who have a long established reputation as the specialist in
this field. Unfortunately, Storage Review had not reviewed this drive at
the time of writing. Although two other sites have reviewed the Momentus 5400.2,
neither review is up to the standards of Storage Review, so those links are deliberately not provided here.

Our test drive was compared against our reference notebook drive,
Samsung MP0402H, that we profiled in a recent
notebook drive review

Two forms of hard drive noise are measured:

  1. Airborne acoustics
  2. Vibration-induced noise.

These two types of noise impact the subjective
perception of hard drive noise differently depending on how and where the drive
is mounted.

Both forms of noise are evaluated objectively and
subjectively. Both the subjective and objective analyses are essential to understanding
the acoustics of the drives. Airborne acoustics are measured using a professional
caliber SLM. Measurements are taken at a distance of one meter above the top
of the drive using an A-weighted filter. Vibration noise is rated on a scale
of 1-10 by comparing against our standard reference drives.

Unfortunately, AAM (Automatic Acoustic Management) is not supported
as a user-configurable option on the Momentus 5400.2, which means that our standard
means of generating seek noise via the AAM test function in Hitachi’s
HDD Feature Tool
could not be used. Instead, seek noise was generated
by copying a large file set within the drive. Unfortunately, this task does
not require as much random seeking as the AAM test, so seek noise was not as
constant as usual. To compensate, we spent more time than usual listening to
and measuring the seek noise.

A final caveat: As with most reviews, our comments
are relevant to the sample we tested. Your sample may not be identical. There
are always some sample variances, and manufacturers also make changes without
telling everyone.

Ambient noise at the time of testing was 19 dBA.

Mfg date
firmware version

(10 = no vibration)

Activity State

Airborne Acoustics

Measured Power
Samsung MP0402H
April 2004
firmware UC100-10

17 dBA/1m

0.8 W
Seek (AAM)

18 dBA/1m

2.3 W
Seek (Normal)

19-20 dBA/1m

2.4 W
Seagate Momentus 5400.2 ST9120821AS
Date Code: 06014
firmware 3.04

20 dBA/1m

1.5 W (heads unloaded)
2.3 (heads loaded)
Seek (Normal)

20-21 dBA/1m

3.3 W

The Momentus 5400.2 exhibits none of the whine that we heard in the last Momentus
we reviewed. It is barely louder than our reference Samsung MP0402H,
and most of the difference is in the low “whoosh” of the spinning
discs. It’s so similar to fan noise that it is almost
guaranteed to be lost in the melange of other sounds in the typical PC, even a quiet one. There is also almost no
high frequency noise —even less than the Samsung — and no humming motor
noise. The noise character is very similar to that of the Western
Digital Scorpio that we reviewed not long ago

As mentioned above, AAM is not supported by the Momentus 5400.2 (or any current
Seagate drive), but this does not prevent the seeks from being inaudible from
a distance of one meter — at least when the drive is placed on soft foam.
Seeks were clearly audible when the drive was placed on our vibration box. Any
seek noise from the Momentus 5400.2 is likely to be vibration-induced. Even
so, they are not loud enough to be bothersome, and may go unnoticed in
a room where the ambient noise is higher than our lab.

Idle vibration was also very good, noticeably lower than the Samsung and on
par with the best we’ve encountered, the Fujitsu MHT2080BH. Even on our highly resonant
vibration test box, it was a challenge to hear the vibration noise for this drive.
Unless the minimal seek noise bothers you, it is safe to say that this drive
does not require decoupled mounting to be quiet.

The power consumption
at idle is 1.5W even with all power saving features enabled. This is significantly
higher than the other notebook drives we’ve tested, which typically idle around
~0.8-0.9W. Likewise, power consumption during seeks was almost a whole watt
higher than any other notebook drive we’ve tested. Relatively speaking, the Momentus could be decribed as “power hungry”, although it’s difficult to apply such a description with a straight face to a device that draws just 3.3W maximum.

To be fair, most of the other drives we’ve tested have had less capacity and
a different interface. The high power consumption may be attributed at least
partially to the use of the SATA interface, which often draws more power than
the same drive with an IDE interface. Its two platters also put it at a disadvantage,
as they require more power to spin than a single platter. Still, the higher
power consumption is something to consider if the drive is intended for use
in a notebook computer where battery power is often more precious than performance.

In actual use, a single watt is not much to worry about for a desktop system. A much greater power saving can be had by undervolting and underclocking the main processor. Of more concern is what the power consumption means for internal heat in a notebook PC. The 5400.2 got quite warm to touch, especially when placed on foam that didn’t conduct heat.

(Chronological order: The most recently reviewed drives are at the top)
Drive Model
(linked to review)

Idle / AAM / Seek

(10 = no vibration)
Subjective Notes
Seagate Momentus 5400.2
20 / – / 20-21
Too close to the Samsung MP0402H to crown either drive as
low noise champion, but a very good choice in any case. Idle noise has
slightly more “wind noise” than the Samsung but no high frequency
noise at all. Although AAM is not supported, seeks are completely inaudible
when placed on soft foam. Consumes more power than most notebook drives.
Digital Scorpio
20 / 21 / 21
Sample variance makes it hard to rank the noise this drive,
but it belongs somewhere between the Samsung notebook series and the Seagate
Barracuda IV. Idle noise is mainly a low frequency motor hum with little
high frequency whine. Seeks are almost too quiet to notice, and can be
characterized as a low rumble. AAM has not effect, but it would be hard
to improve the seeks anyway. Vibration ranged from the level of the Barracuda
IV to below the Samsung MP0402H.
22 / 23-24 / 23-24
Idle noise is rather disappointing; it sounds undamped and
is louder than the Barracuda IV. Seeks are about average for a notebook
drive, rising about 1-2 dBA/1m above idle. The Fujitsu has the lowest
vibration of any drive tested. May avoid the intermittent clicking problem
common with notebook drives because it waits for 10-15 seconds after a
seek before unloading the heads. Consumes ~0.2W more than other notebook
drives in all power states.
17 / 18 / 19-20
The acoustics of this drive are virtually identical
to the Fujitsu MHT2040AT, a considerably slower 4200 rpm drive and the
quietest we’ve encountered. The Samsung is extremely quiet, and there
is very little if any high frequency noise to speak of. It has minimal
vibration, but placing it on soft foam does reduce low freq. noise audibly.
The unit used in the test PC was suspended in elastic string and mostly
surrounded by soft but dense foam. Seek noise is somewhat more audible
than the 1 dBA gain suggests, but very soft.
19 / – / 20
The Hitachi comes very close to the Samsung, but has
a slightly sharper and higher pitched sound, with perhaps a touch more
vibration as well. The seek noise is a touch louder too. When inside
even a very quiet desktop PC, the slightly higher noise level of this
drive over the Samsung may not be audible. The performance is superior,
according to SiSoftware Sandra 2005, and also subjectively.
22 / – / –
Slightly louder than the Seagate Barracuda
IV single platter 3.5″ reference hard drive. The noise signature
has the broadband shhhh quality exhibited by the Samsung
SP 3.5″ drives, but higher in pitch, a bit like the Seagate. A trace
of whine, but not like the Seagate Momentus. Seek noise is only moderately
louder than idle, perhaps by 3 dBA. Vibration is higher than any of the
4200rpm drives; similar to the Momentus. Performance seems quite speedy,
as it should be with 16 MB cache and 5400rpm, but inconsistent results
with all the benchmarks tried stops me from publishing results.
Momentus ST94811A
24 / – / –
The Momentus has a terrible constant “pure”
tone somewhere in the 6~10KHz range. It drops 2-3 dBA in level when
the listener or the mic faces the edge of the drive because of directionality
of the high frequency whine. Seek noise is substantially higher, probably
3~5 dBA. Vibration is much lower than any 3.5″ drive, but higher
than either of the 4200rpm drives tried. A real disappointment, but
it did perform about as fast as or faster than the Seagate Barracuda-IV.
16 / – / –
The only noise maker in the Mappit
PC, which seemed virtually inaudible to me. The noise is not
inaudible, but very low and soft, easily dismissed in the ambient noise
of all but the quietest spaces. There is no high pitched whine to speak
of, and the seek noise does not seem more than maybe 2 dBA higher than
idle. It is the slowest performer of all the drives here. Extremely
low vibration.
16 / – / –
This 8 MB cache 4200 RPM drive offers better performance
than 2 MB cache 4200 rpm drives, and it is identical in both idle and
seek noise to the Fujitsu above. Extremely low vibration.


Barracuda IV ST340016A
21 / 23 / 25-26
In idle, it remains the quietest of all 3.5″ drives.
This sample is almost 2 years old, but seems unchanged in noise. There
may be a touch of high frequency whine but it is very low in level,
and easily obscured when mounted in a PC case. Seek is considerably
higher, possibly as much as 5~6 dBA. Low vibration, but MUCH higher
than any of the notebook drives.
SP0802N (Nidec motor)
21 / 23-24 / 25-26
The idle noise is a touch higher, and its seek may actually
be lower than the Seagate B-IV. Similar vibration level as the B-IV,
but there are reports of some samples exhibiting much higher vibration
levels. This is cured by HDD decouple mounting (suspension in elastic
material or placement on soft foam), which is virtually mandatory for
a truly quiet PC anyway.


An audio recording was made of the drive and saved
in MP3 format. The recordings below contains 10 seconds of idle noise, followed
by 10 seconds of seek noise with AAM enabled and 10 seconds more with AAM
disabled. Because the Seagate does not support AAM, the AAM portion of the recording
was omitted, so for this drive, the recording is only 20 seconds long.

Keep in mind that the audio recordings paint only part of the
acoustic picture; vibration noise is not recorded, and drives often sound different
depending on the angle from which they are heard.

Momentus 5400.2 (Idle: 20 / Seek: 20-21 dBA/1m)

Reference Comparatives:

MP0402H (Idle: 17 / AAM: 18 / Seek: 19-20 dBA/1m)

Digital Scorpio WD800VE (Idle: 20 / AAM: 21 / Seek: 21 dBA/1m)

Barracuda IV ST340016A (Idle: 21 / AAM: 23 / Seek: 25-26 dBA/1m)

Spinpoint P80 SP0802N, Nidec Motor (Idle: 21 / AAM: 23-24 / Seek: 25-26 dBA/1m)

Spinpoint P80 SP0802N, JVC Motor (Idle: 21 / AAM: 25 / Seek: 27 dBA/1m)

Nexus 92mm
case fan @ 5V (17 dBA/1m) Reference


These recordings were made
with a high resolution studio quality digital recording system. The hard
drive was placed on soft foam to isolate the airborne noise that it produces;
recordings do not take into account the vibration noise that hard drives
produce. The microphone was centered 3″ above the top face of the hard
drive. The ambient noise during most recordings is 18 dBA or lower.

To set the volume to a realistic level (similar to the
original), try playing the Nexus 92 fan reference recording and
setting the volume so that it is barely audible. Then don’t reset the
volume and play the other sound files. Of course, tone controls or other
effects should all be turned off or set to neutral. For full details on
how to calibrate your sound system to get the most valid listening comparison,
please see the yellow text box entitled Listen to the Fans
on page four of the article
SPCR’s Test / Sound Lab: A Short Tour.


Our 120GB sample of the Momentus 5400.2 is one of the
quietest drives we’ve tested. Although notebook drives tend to be quieter in general, this one is quiet even for a notebook drive —
only the slowest 4200 RPM drives are likely to be quieter. In short, it is hard
to do better if noise is the top priority and price is no object. As a bonus,
the SATA interface makes it easy to install in a desktop system. There is a big price surcharge for early adopters who want a SATA notebook drive, but this is no surprise. The price is bound to drop as SATA permeates into the notebook PCs in coming months.

Although it boasts the highest capacity of any notebook HDD, 120 GB is not a dramatic gain over the 100 GB that the competition can offer, and it is still far from the 400~500 GB of the highest capacity desktop drives.
The performance bonus from higher areal density is probably more useful to most
users than an extra 20 GB.

The higher power consumption makes the Momentus 5400.2 less than ideal
for a laptop if battery life is critical, but even then a single watt may
not be much to worry about. For a desktop system, it’s of no concern at all; much more than a watt can be saved by undervolting
and underclocking the main processor.

The only question that creeps into mind is whether this sample is representative of most Momentus 5400.2s; and whether the original Momentus sample reviewed was a one-off anomaly. The vast sampling that would have to be tested to verify this is beyond almost any consumer review organization. However, careful readers can certainly help by posting their hands-on experiences with the Momentus drives in the forums.

* * *

Many thanks to Seagate
for the Momentus 5400.2 sample.

Discuss this article in the SPCR Forums.

Leave a Comment

Your email address will not be published. Required fields are marked *