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7. TEMPERATURE & COOLING
The 140mm fan in the X-Pro had no problem keeping things cool. The first time
we saw a temperature rise of over 10°C was at 400W load. The temperature
rise increased considerably above this point, but during most of our testing,
it stayed at a modest 6-8°C. It seems that the heatsinks and the fan do
their job well.
One word of warning: Due to recent changes in our test bench, thermal results
are not perfectly comparable to many of the 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. Earlier tests used
an 80mm exhaust fan which means the newer PSU cooling data may look a bit better;
it may stay cooler to a higher load point.
8. FAN, FAN CONTROLLER and NOISE
The startup / default noise of the fan was 25dBA@1m. This is a few dBA higher
than measured for the quietest PSUs we've reviewed, and audibly louder. The
fan speed remained unchanged to about 150W in our test rig. As soon as the temperatures
increased above a very modest 25°C, the fan voltage began to ramp up. At 200W
load, the noise level rose above 30dBA, which we generally consider the upper
threshold of "quiet".
The relatively high speed of the fan throughout our testing probably helped
the low temperatures that we saw, which would be more important to a high-end
gaming system, but isn't quite what the quiet enthusiast is looking for.
Odd Whistling
The power supply emitted an odd whistling sound as the fan speed began to increase.
It was not coil or capacitor ringing, which could be heard from very close proximity
but low enough to be considered benign. This other noise was most audible directly
in line with the exhaust vent. For many users, the whistling is at a low enough
level that it's not enough to eliminate the X-Pro from contention, but those
with very sensitive hearing and extended high frequency perception may find
it unacceptable.
Surprisingly, when the load was brought up beyond 300W, the whistling stopped
altogether. This was repeatable and consistent, and shows itself in the SPL
drop of 2 dBA from 250W to 300W load.
To be on the safe side, the second sample was brought into play, and the sequence
of load tests were repeated. On the second sample, the whistling noise was absent!
We suspect the whistling is probably an anomaly. We can only conjecture about
the cause:
- The fan in the first sample may be subtly damaged so that its bearings or
fins cause a harmonic noise at certain speeds.
- Wiring and other mechanical impedances arranged uniquely in the first sample
may give rise to the whistly sound when the air velocity through a certain
gap reaches a certain speed.
- Electronic components such as coils and capacitors may be interacting to
cause electromechanical vibration at specific loads.
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 Ultra X-Pro does very well in it's aim of providing a solid powerful PSU
for high power systems. The power output of the X-Pro was nothing short of extraordinary,
with extremely low ripple, and excellent voltage regulation. The overall efficiency
of the PSU was very good as well, helping keep up the standard of high efficiency
PSUs. Electrically, this Ultra is head and shoulders above the earlier X-Inifinity
sample we tested.
The noise levels are still not really up to SPCR standards. The start level
of 25 dBA@1m is not bad, but it's plainly audible, which is not true for the
best PSUs on our recommended list. The fan
speed rises almost linearly with increased load and temperature, which means
that in use within a computer, the PSU's fan speed / noise will tend to go up
and down depending on activity. Such changes in noise level are sometimes worse
than a steady louder noise because they tend to call our attention and thus
become more distracting.
Yes, the X-Pro is quieter than the X-Inifinity, and it's much better electrically.
But it is still not quiet enough to make our recommended list.
If rock-solid stability and good efficiency are your primary concerns, then
the X-Pro power supply will do a very good job of meeting your needs. When you
consider the estimated street price of $100 predicted by Ultra, it's a good
deal. Most good quality 600W PSUs will cost you more. However, if you also seek
low noise, you're better off looking elsewhere.
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SPCR Articles of Related Interest:
Power Supply Fundamentals
Recommended Quiet Power Supplies
Power Distribution within Six PCs
SPCR PSU Test Rig V.4
Seasonic S12 Energy Plus 550 and 650
Mushkin XP-650
Corsair HX520 & HX620
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