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Our sample was 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.
The E7K100 was compared against our reference notebook drive,
Samsung MP0402H, that we profiled in a recent
notebook drive review. It was also compared against the Seagate Momentus
Two forms of hard drive noise are measured:
- Airborne acoustics
- Vibration-induced noise.
These two types of noise impact the subjective
perception of hard drive noise differently depending on how and where the drive
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.
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
Ambient conditions at the time of testing were 18 dBA and 22°C.
Unlike the Momentus 7200.1, the idle noise for the E7K100 was fairly typical
of a notebook drive. The bulk of the noise was a slightly hollow-sounding whoosh
that should easily fade into the residual fan noise of a quiet system. There
was also a slight hum, but it was inaudible beyond about eight inches from the
drive. In comparison to the Samsung reference drive, the E7K100 is clearly louder,
but it is certainly no worse than most other notebook drives.
Even better, seeks with AAM enabled were virtually inaudible... and AAM comes
enabled by default. In fact, they were so quiet that extra care had to be taken
when making the MP3 recordings, since it was not obvious when the drive was
seeking. It should be noted that the measured noise level for AAM is a little
misleading in this respect; subjectively, no difference between idle and AAM
seek could be heard except within six inches of the drive.
The measurements are also misleading about the difference between AAM and normal
seeks. Even though the measured difference was only a single decibel, the subjective
difference was significant: Seeks could be heard clearly in normal mode. Seek
noise was characterized by a rapid ticking, much like the sound of cold drainpipes
cracking (quietly) when a bath is suddenly emptied.
The level of vibration was about the same as both the 7200.1 and the MP0402H.
However, the Hitachi shares a flaw with the Seagate here: Because the drives
spin at 7,200 RPM, the resonant frequency is higher, and therefore easier to
hear. For this reason, the E7K100 will benefit more from soft-mounting than
most other notebook drives.
As mentioned, power management is disabled on the E7K100, so APM was not selectable
from the Hitachi Feature tool. Even so, power consumption at idle was about
average for a notebook drive and better than the Seagate Momentus 7200.1. Power usage for
seeks, on the other hand, was higher. In fact, the E7K100 draws more
power than any other notebook drive we've tested when seeking, beating out the
7200.1 by a small (perhaps negligible) margin. Surprisingly, there was very
little difference in the power draw between AAM and normal seeks.
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