bequiet! Dark Power Pro 10 550W Power Supply

The name is a big mouthful, which fits with the rest of the Dark Power Pro 10 550W — the big packaging, the big casing, and in the end, the big performance. Our first gander at a bequiet! PSU in years, and it manages to catapult past most of the traditional leaders, right to the top of our super-silent, high efficiency, high performance PSU list.

SPCR’s first encounter with this high end BeQuiet power supply occurred at
Computex Taiwan in June 2012. My shorthand notes read, "Wow… sexy!"
and "designed to be seen." The Dark Power Pro 10 series is all that
and more: It is designed to appeal to the demanding computer hound looking for
innovation as well as high performance and precision in a power supply. They
boasts very high efficiency and a host of unusual features.

There are six models in the Dark Power Pro 10 lineup — 550W, 650W, 750W,
850W, 1000W, and 1200W. I thought I’d heard in my chat with BeQuiet reps at
Computex that they were all based on the Seasonic high efficiency X series,
with 80 PLUS Gold or Platinum efficiency, but later, I learned that this is
only true of the higher power models. The 550W, 650W and 750W models are made
by Fortron-Source Power (or affiliate SPI), and rated 80 PLUS Gold. I really don’t see the point of PSU models differentiated by only 100W. In my
book, the 650W and 850W models are superfluous. The model under examination
here is the 550W, which is likely to be of greatest interest for SPCR audiences.

bequiet! is a German company which claims to be the top selling PSU brand in
that country. The brand is not well distributed outside of the EU, however.
Even nearly six months after stating that they would be entering the US market
"very soon", there is no sign of the brand in any US consumer search
engines. Hence the prices cited atop, in British pounds and in Euro dollars,
based on web searches. By today’s exchange rates, the 550W model is selling
for around $130. This is roughly on par with the UK/EU selling price of the
Seasonic X-560, which is a pretty close comparable, although it sells in the
US for about 10% less.

I’ve tested a bequiet! PSU before, the Dark
Power Pro 430, back in 2006. That was pretty quiet in its day. We also
covered a heatsink from this company recently, the Dark
Rock 2.

So, let’s start with a gander at this beauty.

It’s a big retail package. Yes, that’s an 850W sample in the background. Very well packaged and presented in shock-resistant closed cell foam. This photo doesn’t do it full justice; it really looks good. The fan guard is a series of straight wires that gives the PSU its unique look. Rubberized bumpers adorn both back and front. The one on the back serves the real function of damping vibrations that might go from the internal fan to the PC case. The 135mm fan has grooves on each of the seven blades. The output side of the PSU has a single attached cable with the main ATX connector to the motherboard, four PCIe power outlets, five drive outputs, an AUX12V output, a special 12V line switch connector (OCK), and four headers for fans to be controlled by the internal fan controller.

DETAILS

The Dark Power Pro 10 package is extensive, with a huge array of standard parts
and accessories. bequiet! is obviously trying hard to make the buyer feel like
he’s getting lots of value for money.

Clockwise, from the left: There’s the PSU itself, then the AC cable, many bundles of output cables, the impressive looking manual, a bunch of zip and velcro ties, a plug to combine all the 12V lines into one, a back panel switch that allows the user to go instantly between multiple and single 12V lines, a set of mounting screws as well as hefty thumbscrews for the same, and four cables to run case fans off the internal thermal controller. Here’s that switch to go between multiple and single 12V lines. The more permanent single 12V line fix is a plug with a loop of wire. It’s not clear why anyone would want to toggle back and forth… or ever want four 12V lines. A shot of the output specs tag.

INSIDE DP PRO 10 550W

The casing is an unusually complex clamshell design made of sturdy steel sheeting,
with good fit and finish. As mentioned earlier, there are rubber bumpers on
either end. The logo decal on the side is raised and feels like it’s been specially
embossed. A neat illusion.

There was a mention during the meeting with company reps at Computex that special
effort was made to reduce high frequency noise (the dreaded electronic whine)
by using a plastic capactor in the PFC stage. One other nicety: The thermal
controller which feeds the four headers for external fans is apparently separate
from the controller which controls the built in fan, so there’s no chance that
a fan-loving user could overload and burn out the internal fan controller.

OUTPUT CABLES

The output cables are all nicely sleeved, generally long enough for bottom
positioning of the PSU in a large ATX case. A detailed diagram of the cables,
the connectors and the lengths is provided on the box, as well as on their website.
A couple of the cables are worthy of special metion: Two cables, each with a
single SATA or IDE power connector, half a meter long. Those would come in real
handy in some of my builds. Ditto the long cable with two SATA, two IDE and
a floppy drive power connector.

An amazing number of cables for a relatively modestly rated PSU.

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. The DPP 10 550W was tested with all of its 12V lines combined into
a single line.

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
Gold standard requires 87% efficiency at 20% load, 90% efficiency at 50% of
rated load, and 87% efficiency at full rated load.

At the super low 20W load, efficiency was low at 65% but rose
fairly quickly as the load was increased. 80% efficiency was reached around
65W. This sample probably did not quite reach 87% at 20% of rated load (130W);
it was 87.2% at 150W. At 50% load, it fell just about 0.3% short of 90%, but
easily exceeded the required 87% efficiency at full load. I did not test at
higher loads, but the curve had the look of a PSU which might actually produce
significantly higher than rated power, as peak efficiency of >91.2% was reached
at a fairly high 400W, or 73% of rated power. It’s more common to see the peak
efficiency a little bit lower, perhaps at 60%. I would call it a borderline
pass on 80 PLUS Gold — if I was more confident that my Frankensteinish
PSU tester was accurate to that kind of tolerance.

There was no issue with crossloading. With over 90% of a 428W
load on 12V, naturally, efficiency improved 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 very tightly regulated. It started a
touch high at very low load, +0.06V (+0.5%). It dropped gradually as load was
increased, reaching a low of 11.96V (-0.4%) at full power. The 5V line was similarly
tight, starting at 5.04V (+0.8%) and dropping down to 4.95V (-1%) at full load.
3.3V ranged from 3.36V to 3.28V (+1.8% to -0.6%). This is as good as the best
voltage regulation I’ve encountered.

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 excellent
at all power levels, staying under 10mV on 12V at all power levels up to around
350W, and only reaching 25mV momentarily at full load only. The lower voltage
lines ran about half that amount of ripple. This is excellent.

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 was very good for this model, 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, but the
power draw of 13.3W was a little higher than most recently tested PSUs. The
0.4W power draw in standby (power switch on but computer off) is very commendably
low.

6. LOW & 240 VAC PERFORMANCE

The power supply was set to 428W load at various AC input voltages.
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 nearly 94% at 240VAC. The sample passed
the 100VAC minimum input load without any issues, with a 1% drop in efficiency.
Neither voltage regulation nor ripple changed appreciably during these tests.

7. COOLING & NOISE

The fan in the bequiet! Dark Power Pro 10 550W started up at very
low speed and a noise output which, at one meter distance from the microphone,
did not change the 11 dBA SPL ambient in the anechoic chamber. A very soft whirring
could be heard from close up, say about a foot away, but in any normal operating
situation, this PSU would be silent to over 400W, where a rise of just 1 dBA,
to 12 dBA@1m, was measured. At 500W load, the fan sped up enough for it to register
13 dBA, and full power finally brought us to 15 dBA@1m. This is quieter than
many power supplies at minimum load, and such power supplies are considered
very quiet by most users. The sound was never more than a gentle broadband woosh,
and there was no audible whining or buzzing electronic noise at low loads, although
at full load, a bit of buzzing could be heard at a low level beneath the broadband
whoosh of the fan, but again only from a very close distance. In normal use,
this DPP 10 550W could be easily mistaken for a fanless unit.

The exhaust air temperature was not unduly high, reaching a maximum
of just 41°C at full load with room ambient at 23°C. This is about average for
a PSU at this power load. We can only conjecture about the temperature of actual
components inside the PSU, but this comment holds true for all PSUs tested by
all computer hardware review sites.

IN THE HOT BOX

When exposed to the heat of the hotbox, the bequiet! Dark Power
Pro 10 550W fan started to spin up at a lower power level, and ran considerably
faster, but the overall noise profile remained very smooth and benign. Even
in an old-style case with poor fresh air intake for the PSU, the DPP 550W will
remain quiet to over 400W load. This is very good performance.

8. FAN HEADERS

One of the four external fan headers was used during the testing to drive a
120mm fan rated at 1500 RPM — like the internal PSU fan — with its
RPM lead monitored by a fan header on our lab test PC. Voltage could also have
been monitored, but this is probably just as informative.

What the above information tells us is that one to four smooth sounding case
fans rated for 1500 RPM (or perhaps as low as 1200 RPM, for reliable startup)
could be mounted in the system, and unless your case configuration is terrible,
those fans would probably not become significantly audible until past 400W load
(or 450W measured at the AC outlet). This is a perfectly useful fan control
profile for silent PC enthusiasts.

COMPARISONS

The comparison table below shows the SPL versus Power Load data on PSUs tested
in ambient room temperature, typically 20~24°C. It is most relevant when PSUs
are used in cases that provide wide open access to cooler outside air for the
PSU cooling fan. The bequiet! Dark Power Pro 10 550W jumps to the top of the
list. It probably belongs at the very top — the 15 dBA at 500W cited in
the table is not strictly accurate; at 500W it’s 13 dBA, and reaches 15 dBA
at 550W, but it would have been awkward to insert another column at 550W.

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.
The bequiet! DDP 10 550W only falls below the fanless Seasonic X-400 (and X-460,
if it was on this table) up to 400W. At full 550W output, its only competitor
here is the Enemax Platimax 600W.

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 bequiet! Dark Power Pro 10 550W lives up to the promise
of its good looks, the elaborate packaging and the marketing hype: It is extraordinarily
quiet, extremely proficient from an electronic power point of view, and actually
represents decent value at the current UK£90 selling price (without
VAT). The flexibility offered by the array of output cables and those four independent
thermally controlled headers for fans are quite worthwhile. The fan headers
could easily eliminate headaches about how to keep case fans from ramping up
noisily without risking overheating under high load. That saves worrying about
whether your motherboard has a good built-in fan controller or having to spend
more of your hard-earned money on an external multi-channel fan controller and
further complicating the internal wiring.

Those fancy rubber bumpers probably don’t do anything given the
slow speed that the fan runs at through 95% of its rated power, but they don’t
hurt either. The mechanical integrity of the casing provided by the many screws
that hold the two clamshell halves together probably helps to minimze vibration,
too.

About the only charge that could be laid is that (at least this
sample) just barely makes the 80 PLUS Gold grade… but I’m not making that
charge, as it comes so close on both the 20% and 50% loads, and exceeds the
standard at full load. The real quibble for North American PC enthusiasts is
that bequiet! products still haven’t made it over the Atlantic. I’m looking
forward to seeing what the Seasonic-built 850W Platinum model will do.

* * *

Much thanks to bequiet! for the review sample.

bequiet! Dark Power Pro 10 550W earns SPCR’s Editor’s Choice Award

* * *

SPCR Articles of Related Interest:
Power Supply Fundamentals

Recommended Power Supplies
SPCR PSU Test Rig
Enermax Platimax 600W
Kingwin
Stryker STR-500
Seasonic G360
Enermax Modu87+ 500W 80 Plus Gold

Seasonic X-650: Seasonic Hits
Gold
CoolerMaster Silent
Pro M2 720W PSU

* * *

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