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7. TEMPERATURE & COOLING
Thermal results were acceptable, despite the smaller heatsinks. The thermal
rise through the unit remained at roughly 6°C through all of the tests except
for full load when it jumped up to about 12°C. Given that the exhaust temperature
only barely reached the maximum operating temperature, it seems safe to say
that the Earth Watts is well cooled.
One word of warning: Due to recent changes in our test bench, thermal results
are not directly comparable to earlier tests that we have done. Our new test
bench uses a larger 120mm fan that provides a more realistic simulation of the
kinds of low-noise systems that are in use today.
8. FAN, FAN CONTROLLER and NOISE
As any change to airflow also affects noise, the same caveat applies to our
noise results; noise results for the Earth Watts are not comparable to earlier
reviews. We do not believe that the change is large, but the larger fan will
certainly have an effect; the increase in airflow can be expected to delay the
point when the fan increases in speed. Cooler temperatures inside the test bench
mean that the power supply doesn't have to work as hard to keep cool, and it
can therefore run more quietly Another possible point of change is the fact
that the larger fan may let out more noise than previously.
Although the Earth Watts has almost the same starting voltage as the Neo HE,
it was slightly but audibly louder at minimum speed. Most significantly, it
produced a low hum that was absent in the Neo HE. The measured difference may
only have been 2 dBA@1m, but the subjective difference was easy to notice. That's
not to say that the Earth Watts was loud, exactly, but it didn't quite fall
into the "practically inaudible" category that made the Neo HE so
special.
The fan controller in the Earth Watts was quite good, remaining at minimum
until approximately ~200W output and remaining reasonably quiet even at 250W.
Gaming systems may be able to stress the power supply enough to push the fan
up above this, but most systems should have no problem staying within a 200W
envelope. However, once the fan had started to change speed, it proved to be
fairly sensitive, and changes in fan speed occasionally drew attention to themselves.
MP3 SOUND RECORDINGS
Each of these recording have 10 seconds of silence to let you hear the ambient
sound of the room, followed by 10 seconds of the product's noise.
Sound Recordings of PSU Comparatives
HOW TO LISTEN & COMPARE
These recordings were made
with a high resolution, studio quality, digital recording system, then
converted to LAME 128kbps encoded MP3s. We've listened long and hard
to ensure there is no audible degradation from the original WAV files
to these MP3s. They represent a quick snapshot of what we heard during
the review. Two recordings of each noise level were made, one from a
distance of one meter, and another from one foot
away.
The one meter recording
is intended to give you an idea of how the subject of this review sound
in actual use — one meter is a reasonable typical distance between
a computer or computer component and your ear. The recording contains
stretches of ambient noise that you can use to judge the relative loudness
of the subject. For best results, set your volume control so that the
ambient noise is just barely audible. Be aware that very quiet subjects
may not be audible — if we couldn't hear it from one meter, chances
are we couldn't record it either!
The one foot recording is
designed to bring out the fine details of the noise. Use this recording
with caution! Although more detailed, it may not represent how the subject
sounds in actual use. It is best to listen to this recording after you
have listened to the one meter recording.
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CONCLUSIONS
The Earth Watts may be aimed squarely at the (emerging?) Green computing market,
and worthy of praise on other merits. It's highly
efficient thanks to an 80 Plus certified design, it has excellent electronics
(as demonstrated by our rigorous electrical tests), and it's pretty quiet
too. Pricing is also very good for a good quality power supply. There's much to like here, and very little to dislike.
Still, we're not really sold on the "Green" aspects of the Earth Watts.
High efficiency, active PFC, and the required RoHS compliance all make good
selling points for the Green conscious, but these features are not unique
to the Earth Watts — all of these are hallmarks of good quality power supplies,
"Green" or not. And how much impact does the extra efficiency
have, anyway? We're all for efficiency and being environmental friendliness, but
we find it hard to believe that the energy saved by the extra efficiency is
all that great, especially at the 40~60W level that a well-designed system should
idle at. The 6~8W difference between 60% and 70% efficiency at this level just
doesn't seem like much. It's certainly not enough to justify buying a replacement
power supply if the environment has to bear the cost of putting the old power
supply in a landfill.
On the other hand, if you're in the market for a new power supply, and
your needs run towards the thrifty and the efficient rather than the flashy
and the powerful, the Earth Watts may be one of the best there is. To our knowledge,
the 380W model is the smallest 80 Plus certified power supply on the retail
market at the moment.
So, of Antec's two "efficient" PSU models (the Neo HE and the Earth
Watts), which would we choose? That's a tough question because it depends on
your priorities. There's no doubt that the Earth Watts is the more efficient
of the two, but it's equally clear that the Neo HE has less residual noise.
This being Silent PC Review, we'd lean towards the Neo HE, especially
for lower power systems where the lower efficiency is less significant and the
fan is unlikely to ramp up. For more powerful systems, the choice is less clear:
Do you go with the lower residual noise of the Neo HE, or do you get the Earth
Watts so that the fan is quieter when the system is under load? Much depends
on how noisy the rest of the system is.
The Earth Watts seems best suited to systems where absolute silence
is not the goal. It's quiet enough for general use, especially in mid-range
gaming systems where the graphics card is likely to drown out any noise from
the power supply unless the fan ramps up. Extreme silencers may prefer a Neo
HE, and high-end enthusiasts will no doubt want one of Seasonic's designer power
supplies, but the Earth Watts seems like a good quality mainstream choice.
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SPCR Articles of Related Interest:
Power Supply Fundamentals & Recommended
Units
Power Distribution within Six PCs
SPCR PSU Test Rig V.4
FSP Green PS
Seasonic S12 Energy Plus
Antec NeoHE 430
Silverstone Element Plus ST50EF-Plus
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