Rosewill Silent Night 500 Platinum 80 Plus

Rosewill may be a house brand, but Newegg has enough muscle to attract strong partners. In the case of the Silent Night 500 Fanless 80+ Platinum PSU, Rosewill’s partner Super Flower has given Rosewill a major win.

Rosewill is Newegg’s house brand, although their products are ostensibly
offered at many other outlets. Before you shun it as a line of generics,
Rosewill claims their focus is on both value and price, and my scan of Newegg
user reviews (not exactly an impartial source, admittedly) suggests quality
is above par. This is our first look at a Rosewill branded product. The Silent
Night 500W was pointed out by Rosewill’s Marketing Manager Chinny Chung as a
suitable product for SPCR to review, an opinion most readers will agree with
whole heartedly: It is a fanless PSU of the highest efficiency rating currently
available.

The retail package is fairly modest in size by current standards, and modest overall. No shouty colors here… but then this is a Newegg house brand, and they’ve got to know better than anyone that package cosmetics mean little when selling on line. The back side of the box is plain indeed, providing basic information. The internal packaging is good, with closed-cell foam (preferred over styrofoam) used for shock protection. All the contents: A pouch for the detachable cables, the PSU itself, a paper user guide, AC cord, four zip ties, and bag of both screws and thumbscrews for PSU mounting.

Deja vu was the feeling upon opening up the package: The Rosewill Silent Night
500 is obviously a rebadge of the Kingwin
Stryker STR-500. At time of writing, the two products are priced identically
at Newegg: $159.99. Outside the US and Canada, Super Flower is the name associated
with this product. The performance of the Stryker STR-500 was excellent, and
there is little reason to expect the Silent Night to be different. We can consider
it an opportunity to test a second sample 18 months later, especially against
the newer standard-setting Seasonic
520W Platinum fanless PSU released last year.

DETAILS

The casing is unchanged from the Kingwin Stryker STR-500 reviewed previously.
A hefty anodized aluminum extrusion with short ribbed fins is one of the 170x150mm
panels, and it serves to dissipate the heat from hot component clamped to the
flat inner side. The other 170x150mm panel is part of a U-shaped chassis panel
made of reasonably sturdy steel sheet metal, and it has no vents. The other
four sides are mostly perforated.

A well-vented passively cooled PSU usually becomes an intake channel especially
when positioned near a back panel case exhaust fan. So despite the passive cooling
design, in PC cases that utilize any forced airflow for cooling, the Silent
Night 500 will usually enjoy some peripheral airflow. This has the effect of
raising the temperaure of the air that gets drawn in through the PSU, but the
heating effect will be minimal with such a high efficiency model.

The external appearance of the Rosewill Silent Night 500 is almost identical to that of the Kingwin / Super Flower 500W fanless. A large external aluminum heatsink is the "bottom" panel, and all other sides except the top are generously vented. The heatsink panel does have two rectangular vents, perhaps over parts that run extra-hot. Here is where a minor departure from the Kingwin shows up: The four output connectors are of a slightly different rectagular 8-pin design, compared to the square 9-pin connectors in the Kingwin. It is a semi-modular design, with main ATX, AUX12V and PCIe output connectors all on fixed cables. Only the HDD/peripheral power cables are detachable. Label on the PSU.

OUTPUT CABLES

The fixed main ATX, AUX12V and PCIe cables are "normal", nicely sleeved.
All the detachable output cables are flat data-style. My guess is that there
is some small savings in labor cost; the flat cables do not require sleeving.

TESTING

For a fuller understanding of ATX power supplies, please read
the reference article Power
Supply Fundamentals. Those who seek source materials
can find Intel’s various PSU design guides at Form
Factors.

SPCR’s
PSU Test Platform V4.1. is the basic setup for the testing. It is a close simulation of
a moderate airflow mid-tower PC optimized for low noise. There is one major change: The primary testing is done with the PSU NOT inside the hotbox but atop it, out of the heat path. This is in recognition of several realities that prevail today:

• In SPCR’s earlier test platforms, the internal temperature varied proportionately
  with output load. The tested PSU was subject to this heat, and operating ambient
  temperature rose with increased load, reaching >40°C and often much
  higher at full power. This was a realistic simulation of a mid-tower PC case
  where the PSU is mounted conventionally at the top back portion of the case.
• The vast majority of "serious" PC cases for the home builder place no longer position the PSU at the top back corner. They put the PSU at the bottom/back corner, mostly out of the path of heat from the other components in the case. This design concept took root with the Antec P180 going back over 5 years, and dominates the DIY case arena. This means the PSU generally has to dissipate only its own heat.

Now, we’ve reversed our approach: The PSU is tested briefly in
the hotbox only to check what happens to noise, fan speed and temperatures when
it is used in an outmoded case design.

Acoustic measurements are performed in our own anechoic chamber with ambient level of 11 dBA or lower, with a PC-based spectrum analyzer comprised of SpectraPLUS software with ACO Pacific microphone and M-Audio digital audio interfaces.

REAL SYSTEM POWER NEEDS: While we test the PSU to full
output in order to verify the manufacturer’s claims, real desktop PCs simply
do not require anywhere near this level of power. The most pertinent range of
DC output power is between about 40W and 300W, because it is the power range
where most systems will be working most of the time. It is true that very elaborate
systems with the most power hungry dual video cards today might draw as much
as another 150~300W, but the total usually remains under 600W.

TEST RESULTS

The ambient temperature was ~22°, and the ambient noise level
was ~10 dBA.

1. EFFICIENCY — This is a measure of AC-to-DC
conversion efficiency. The ATX12V Power Supply Design Guide recommends 80% efficiency
or better at all output power loads. 80% efficiency means that to deliver 80W
DC output, a PSU draws 100W AC input, and 20W is lost as heat within the PSU.
Higher efficiency is preferred for reduced energy consumption and cooler operation.
It allows reduced cooling airflow, which translates to lower noise. The 80 PLUS
Platinum standard requires 90% efficiency at 20% load, 92% efficiency at 50%
of rated load, and 89% efficiency at full rated load.

At the super low 20W load, efficiency was 70%. It rose to 78%
at 40W. At 50% load, it exceeded the required 92% efficiency, and hit the high
of 93.2% at 300W. At full load it was 89.8%, still over the required 89% efficiency.
The differences in efficiency seen among the three 80+ Platinum fanless PSUs
we’ve tested are marginal under most conditions.

There was no issue with crossloading. With over 90% of a 400W
load on 12V, efficiency improved a smidgen over the standard loading.

2. VOLTAGE REGULATION refers to how stable the output voltages
are under various load conditions. The ATX12V Power Supply Design Guide calls
for the +12, +5V and +3.3V lines to be maintained within ±5%.

The critical 12V line was well regulated. It started a touch high
at very low load, 12.18V (+1.5%) and dropped gradually as load was increased,
reaching a low of 11.94V (-0.5%) at full power. The 5V line was similarly stable,
starting at 5.18V (+3.6%) and dropping to 4.95V (-1.0%) at full load. The 3.3V
line went from 3.36V (+1.8%) at minimum load to 3.2V (-3%) at full load. This
is very good performance, similar to that of the Kingwin Stryker STR-500, but
not up to the even more rock-stable voltage regulation of the Seasonic Platinum
520W.

3. AC RIPPLE refers to unwanted "noise"
artifacts in the DC output of a switching power supply. It’s usually very high
in frequency (in the order of 100s of kHz). The peak-to-peak value is measured.
The ATX12V Guide allows up to 120mV (peak-to-peak) of AC ripple on the +12V
line and 50mV on the +5V and +3.3V lines. Ripple on all the lines was very good
at all power levels, staying under 16mV on 12V at all power levels up to around
250W and increasing gradually with power to <28mV at full load. The ripple
on the 5V and 3.3V lines was consistently ~40% lower than on the 12V line.

4. POWER FACTOR is ideal when it measures 1.0. In the most
practical sense, PF is a measure of how "difficult" it is for the
electric utility to deliver the AC power into your power supply. High PF reduces
the AC current draw, which reduces stress on the electric wiring in your home
(and elsewhere up the line). It also means you can do with a smaller, cheaper
UPS backup; they are priced according to their VA (volt-ampere) rating. Power
factor is excellent, running 1.0 through most of the loads.

5. LOW LOAD TESTING revealed no problems starting at very
low loads. Our sample had no issue starting up with no load, either, and the
power draw of 7.9W was very low. The 0.3W power draw in standby (power switch
on but computer off) is the best measured.

6. LOW & 240 VAC PERFORMANCE

The power supply was set to 400W load and the AC input voltage
varied. Most full-range input power supplies achieve 2~3% higher efficiency
with 220~240 VAC, compared to 110~120 VAC. SPCR’s lab is equipped with a 240
VAC line, which is used to check power supply efficiency for the benefit of
those who live in higher mains voltage regions. We also used a hefty variac
to check the stability of the PSU under brownout conditions where the AC line
voltage drops from the 120V norm.

Efficiency improved to 95.2% at 240VAC. This matches the efficiency
of the Seasonic 520W Platinum, a level never been reached by any other PSU in
over 10 years of SPCR testing. The sample passed the 100VAC minimum input load
without any issues, with a 0.7% drop in efficiency. Neither voltage regulation
nor ripple changed appreciably during these tests.

7. COOLING

The temperatures marked in the main test results table need some
explanation. Normally, for a fan-cooled PSU, a thermal sensor is moved around
a bit during warmup at ~200W load to find the "hot spot" on the exhaust
grill where is attached using friction. This provides consistent enough readings
of the exhaust air temperature. With a fanless PSU, there is no force airflow,
so where should the sensor go? For the Rosewill Silent Night 500, it was placed
on the back panel grill, on the edge od the heatsink panel. This temperature
data is probably not very useful. To be honest, without an array of thermal
sensors placed at many spots all around the interior, monitoring the temperature
of a fanless PSU is futile. In any case, the unit did not suffer any temperature
overload shutdown during the testing, even at full load when the outer casing
temperature exceeded 50°C in a couple of spots.

8. NOISE

No noise of any kind was heard or detected at low load in the
anechoic chamber with the microphone a meter away. Even from virtually inches
away, not even a trace amount of whine or buzz could be reliably heard; a noise
might have been there, but it was below my threshold of hearing sensitivity.

The noise was checked repeatedly as load was increased. At around
the 200W load, a trace level of buzzing became audible from inches away, but
too low in level to be at all significant in any application. It was inaudible
from a foot away, nor was it measurable; ie, it was below the 10 dBA ambient
noise floor of the chamber.

This trace buzz did continue to rise proportionately with increased
load so that at full load (500W), the buzz was just barely audible from a meter
away, and registered about a 1 dB rise in sound pressure level (SPL), to perhaps
11.5~12 dBA @1m. Most of the buzz was centered around 300Hz, like the Kingwin
version tested before. In normal use, this would still be inaudible unless the
PSU was working in a super quiet environment and in a system without any other
noise sources (like fans), which would be quite a feat if the components were
drawing 500W — that’s too much heat to be disspated without forced airflow
unless you’ve got some custom-built, massive, passive heatsink/case.

The Rosewill Silent Night 500 is effectively silent as claimed.
It is a bit quieter at full load than the Kingwin STR-500 sample tested 18 months
ago.

COMPARISONS

The comparison table below shows the SPL versus Power Load data on PSUs tested
in ambient room temperature, typically 20~24°C. By SPL at 1m, only the Seasonic
520 Platinum Fanless tops it at full load, but that model has a history of somewhat
more significant electronic noise.

The comparison table below shows the SPL versus Power Load data on all the
PSUs tested in the hotbox. It’s difficult to rank them, as the measured SPL
varies differently with power load. The units which are quietest at minimum
load are not always the quietest at midload (100W~300W), which may make them
louder in actual use. Then there’s the noise level at 400W and up, which will
determine the quietest PSUs for high power gaming rigs, during actual gaming.
Again only the Seasonic 520 Platinum edges the Rosewill Silent Night 500, and
this assumes the Seasonic is free of electronic noise.

Caution: Please keep in mind that
the data in the above table is specific to the conditions of our test setup.
Change the cooling configuration, the ambient temperature and any number of
other factors, and you could change the point at which the fans start speeding
up, as well as the rate of the rise in speed. The baseline SPL is accurate,
however, probably to within 1 dBA.

CONCLUSIONS

The Rosewill Silent Night 500 power supply delivers excellent
performance by any standard. Its voltage regulation, noise and ripple, and efficiency
are all top notch, with the efficiency being as high as I’ve measured in any
PSU thus far. The >95% efficiency at 400W load with 240VAC input means this
PSU produces only 20W of heat, a trivial amount. The 5 years parts & labor
warranty bolsters buyer confidence as well.

This sample produced virtually no audible electronic noise under
~200W, and at full power, its electronic noise was lower than all but the best
of three 520W Seasonic Platinum samples I tested. Admittedly, the more recent
design Seasonic 520W Platinum has tighter voltage regulation — the best
ever — but that’s about the only area where the Seasonic has a clear advantage.
In actual use, the advantage may be moot; there are no computer components which
actually demand such tight voltage regulation for normal operation.

About the only possible quibble one might have about the Rosewill
SN500 is that it is a bit heavy, probably not ideal for top rear mounting in
a thin-panel aluminum case if it’s being shipped. The very low power efficiency
is not quite as good as the Seasonic Platinum, but then this is a matter of
only a watt or two at most. Finally, you might have to face snide remarks from
tech geek friends about why you’ve chosen a house brand… and if you do, just
send them the link to this review: The Rosewill Silent Night 500 is worthy of
the SPCR Editor’s Choice Award.

* * *

Much thanks to Rosewill for the review sample.

Rosewill Silent Night 500 PSU wins the SPCR’s Editor’s Choice Award

* * *

SPCR Articles of Related Interest:
Power Supply Fundamentals

Recommended Power Supplies
SPCR PSU Test Rig
Seasonic Platinum
Fanless 520W
Fanless PSU Torture
Test Roundup
Fanless
PSUs: Kingwin Stryker STR-500 & Silverstone ST50NF
Seasonic X-400 Fanless
PSU
Enermax Platimax 600W
Seasonic G360

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