vacancies advertise contact news tip The Vault
facebook rss twitter

Review: be quiet! Dark Power Pro 11 550W

by Tarinder Sandhu on 8 September 2015, 12:00

Tags: be-quiet

Quick Link: HEXUS.net/qacuhj

Add to My Vault: x

Running the numbers

Our testing procedures can be found at this link.

Efficiency

Load 10pc 25pc 50pc 75pc 100pc
Efficiency - be quiet! DPP 11 550W 85.3pc 90.2pc 94.1pc 92.2pc 91.5pc
Efficiency - be quiet! DPP 11 850W 86.1pc 91.0pc 94.2pc 92.6pc 91.5pc

We've not tested any medium-wattage PSU bearing the 80 PLUS Platinum certification, so to get an idea of where it sits in relation to the best supplies, we're comparing it directly against its bigger brother, the 850W version.

Efficiency is good considering the supply is rated at 550W. It's more likely that it's a de-rated 700W to achieve the lower capacity.

Regulation

In terms of regulation, we're looking at just how well the supply is able to hold to the various lines. The ATX spec. has a +/- 5 per cent leeway on all but the -12V line.

Line/Load 3.3V 5V 12V
10 per cent - be quiet! DPP 11 550W +1.0pc +0.5pc +0.3pc
10 per cent - be quiet! DPP 11 850W +0.8pc +0.3pc +0.3pc
50 per cent - be quiet! DPP 11 550W +0.5pc +0.4pc +0.9pc
50 per cent - be quiet! DPP 11 850W +0.6pc +0.5pc +0.7pc
100 per cent - be quiet! DPP 11 550W -0.5pc -0.4pc -0.5pc
100 per cent - be quiet! DPP 11 850W -0.7pc -0.2pc -0.4pc

Most supplies overvolt with little load and undervolt when stressed. The two Dark Power Pro 11 models are pretty similar, with both being excellent, and we're impressed that we see so little leeway across the board.

Regulation - cross-load

How about providing uneven loads that stress particular voltage rails? In the first attempt, we've put 40A on the 12V rails, and 1A on the 3.3V and 5V rails. This can actually be somewhat typical for a system heavy on graphics and CPU power. In the second, we've turned the tables and gone for 12A on both the 3.3V and 5V rails - highly unlikely in a real-world environment - and just 2A on the 12V - even more unlikely!

Line/Load 3.3V 5V 12V
Cross-load 12V focus - be quiet! DPP 11 550W +1.0pc +0.7pc -0.6pc
Cross-load 12V focus - be quiet! DPP 11 850W +1.1pc +0.8pc -0.4pc
Cross-load 3.3V/5V focus - be quiet! DPP 11 550W -1.3pc -0.6pc +0.4pc
Cross-load 3.3V/5V focus - be quiet! DPP 11 850W -1.5pc -0.7pc +0.3pc

Hammering one part of the PSU power delivery while using just a small portion of the other can throw cheaper supplies of out kilter. Impressive numbers once again.

Ripple

Line/Load (mv - p-p max) 3.3V 5V 12V
10 per cent - be quiet! DPP 11 550W 10mV 15mV 25mV
10 per cent - be quiet! DPP 11 850W 10mV 15mV 25mV
50 per cent - be quiet! DPP 11 550W 15mV 15mV 30mV
50 per cent - be quiet! DPP 11 850W 15mV 15mV 25mV
100 per cent - be quiet! DPP 11 550W 15mV 20mV 35mV
100 per cent - be quiet! DPP 11 850W 15mV 20mV 30mV

The ATX v2.2 spec states that the maximum permissible ripple is 120mV for the 12V line and 50mV for others.

PSUs convert AC power into DC, but doing so requires the AC waveform to be suppressed. What we're really testing here is the quality of the supply's rectifier and any smoothing capacitors in getting rid of this unwanted up-and-down ripple - the raison d'être of this supply.

The two supplies are very close, with the 550W model having just a fraction more ripple on the 12V line.

Temps

Temperatures Intake Exhaust
10 per cent - be quiet! DPP 11 550W 28°C 32°C
10 per cent - be quiet! DPP 11 850W 28°C 31°C
50 per cent - be quiet! DPP 11 550W 30°C 34°C
50 per cent - be quiet! DPP 11 850W 31°C 34°C
100 per cent - be quiet! DPP 11 550W 38°C 40°C
100 per cent - be quiet! DPP 11 850W 39°C 42°C

Platinum-rated efficiency has the ancillary benefit of producing very little heat. Being close to 95 per cent efficient at 50 per cent means the fan doesn't have much work to do in order to keep the unit working at sensible temperatures.

Fan performance

Temps are good but they mean little in isolation. Obtaining accurate noise readings is near impossible when the supply is connected to the Chroma test harness and dual-unit load-tester. We can test the manufacturer's quietness claims in a different way, by using an AMPROBE TMA10A anemometer placed directly over the centre of the PSU. The anemometer records the airflow being pushed/pulled from the PSU's fan. We can use a Voltcraft DT-10L RPM meter to measure the rotational speed of the fan, too.

Load Fan RPM Airflow Noise
10 per cent - be quiet DPP 11 550W 250rpm 15cfm Very quiet
10 per cent - be quiet! DPP 11 850W 300rpm 15cfm Very quiet
50 per cent - be quiet DPP 11 550W 450rpm 20cfm Very quiet
50 per cent - be quiet! DPP 11 850W 520rpm 20cfm Very quiet
100 per cent - be quiet DPP 11 550W 900rpm 40cfm Very quiet
100 per cent - be quiet! DPP 11 850W 1,100rpm 45cfm Quiet

We couldn't hear the fan noise above the other components in the Chroma system. You would do very, very well to hear the SilentWings 3 in an already-quiet system. The supply appears to live up to its be quiet! name.