Reviews - beQuiet Dark Power Pro 10 550W
Sample Provided by: be-quiet (By jonny on Mon, Jun-11-2012)

Page 3 - Testing the power supply unit

For testing, I plug the power supply into a Sun Moon SM-8800; a piece of test equipment used to load up ATX power supplies. The load tester is programmed to put 10 different loads on the PSU: 10%, 20%, 30%, 40%, 50%, 60%, 80%, 100%, all of the load on just the +12V rail and the, finally, all of the load on the +3.3V and +5V rails. The exhaust created by making this loads are vented into the intake of the power supply. This is done so the power supply is operating in an environment more similar to what it would be operating in when installed in a PC chassis.

At each load, I measure the voltage of each rail, the wattage the PSU is putting out, the wattage the PSU is pulling from the wall, the power factor, the temperature of the air being sucked into the power supply and the exhaust air coming out of the back of the power supply.

beQuiet! Dark Power Pro P10-550W HOT load tests
Test #
+3.3V
+5V
+12V
+5VSB
DC Watts/
AC Watts
Eff.
Power
Factor
Intake/
Exhaust
Simulated system load tests
Test
0
0A
0A
0A
1.5A
7.5W/
10.28W
73%
.51
24°C/
24°C
     
4.93V
Test
1
1.3A
1.3A
3.0A
1.5A
111.1W/
131.2W
84.7%
.98
24°C/
27°C
3.34V
5.03V
12.15V
4.94V
Test
2
2.7A
2.7A
6.7A
1.5A
166.9W/
190.8W
87.5%
.99
26°C/
29°C
3.33V
5.03V
12.15V
4.94V
Test
3
4.0A
4.0A
10.4A
1.5A
166.9W/
191W
87.4%
.99
27°C/
30°C
3.33V
5.03V
12.15V
4.94V
Test
4
5.3A
5.3A
14.0A
1.5A
221.1W/
250W
88.4%
.99
28°C/
33°C
3.32V
5.02V
12.14V
4.94V
Test
5
6.6A
6.6A
17.7A
1.5A
276.7W/
310.7W
89.1%
.99
29°C/
34°C
3.31V
5.01V
12.14V
4.94V
Test
6
8.0A
8.0A
21.4A
1.5A
333.0W/
373.5W
89.2%
.99
31°C/
36°C
3.30V
5.00V
12.13V
4.94V
Test
7
10.6A
10.6A
28.7A
1.5A
442.3W/
498.1W
88.8%
.99
33°C/
40°C
3.28V
4.99V
12.12V
4.93V
Test
8
13.2A
13.2A
36.0A
1.5A
551.2W/
624W
88.3%
.99
37°C/
44°C
3.26V
4.97V
12.11V
4.93V
Test
CL1
0A
0A
45A
0A
545.5W/
614W
88.8%
.99
42°C/
48°C
3.31V
5.01V
12.13V
5.05V
Test
CL2
13.2A
13.2A
44A
0A
109.6W/
132.5W
82.3%
.98
33°C/
38°C
3.30V
5.01V
12.15V
5.05V

First, let's analyze the voltage regulation. We see a drop in the +3.3V rail, going from +3.34V to +3.26V. That's a drop of 0.08V, or 2.4%, which is average for a +3.3V rail that uses DC to DC for regulation. The +5V dropped from +5.03V to +4.97V, which is a drop of 0.06V, or 1.2%, which is above average for a DC to DC rail. The +12V dropped from +12.15V to +12.11V. This is phenomenal as it represents a drop of only 0.04V, or 0.3%.

Next, let's look at the efficiency. Specifically, we want to look at test 2, 5 and 8 as these represent 20%, 50% and 100% loads, which is what 80 Plus uses to judge what "grade" to categorize a PSU under. My loads are not the same as what is used for 80 Plus. To make reviews between different power supply makes and models fair, I use a formula to determine how much to load up each rail. In my tests, the Dark Power Pro has an efficiency of 87.5%, 89.1% and 88.3%. That means we're efficient enough at 20% and 100% loads for 80 Plus Gold and just shy at 50%. Given a slight margin of error, this is close enough to still call 80 Plus Gold.

Now let's retest the power supply using 80 Plus's loads to see if we can get even closer to the 80 Plus Gold claims made on the box.

be-quiet Dark Power P10-550W 80 Plus load tests

Test #

+3.3V

+5V

-12V

+12V

+5VSB

DC Watts/
AC Watts

Eff.

Simulated system load tests

20%

2.2A

2.2A

0.1A

7.4A

0.5A

111.6W/
130.3W
85.6%

3.32V

502V

-12.23V

12.15V

4.99V

50%

5.4A

5.4A

0.2A

18.5A

1.2A

276.5W/
311.2W

88.8%

3.27V

4.99V

-12.12V

12.13V

4.93V

100%

10.8A

10.8A

0.4A

37A

2.5A

549.9W/
629.1W

87.4%

3.18V

4.92V

-12.14V

12.10V

4.78V

Having changed the loads, I'm now missing 80 Plus Gold more at 20% and 50%, but I'm still at 80 Plus Gold levels at 100% load.

Next we're going to have a look at the ripple and noise:

Oscilloscope Measurements for beQuiet Dark Power Pro P10-550W
Test #
+3.3V
+5V
+12V
+5VSB
Test 1
Test 2
Test 3
Test 4
Test 5
Test 6
Test 7
Test 8
Test 9
(CL 1)
Test 10
(CL2)

The +3.3V, +5V and +5VSB have almost no ripple and only a little bit of noise. The +12V also only has a little bit of noise, but the sine wave we're seeing shows us that we have some ripple that hasn't been smoothed out. Right off the bat, we see 25mV. By test 5, this increases to 50mV. This is well within the ATX specification of 120mV, but not something we see often in high end power supplies.

Finally, we're going to have a look for overshoot transients:

Overshoot Transient Testing for beQuiet Dark Power Pro P10-550W
Off to VSB On
VSB to Full, 12V
Off to Full, 12V

Going from full off to a full load on the +5VSB, we see a tiny little bit of an overshoot, but nothing at all alarming. The +12V rail, both coming from a stand by state and a full off state, has no overshoot at all. The rise time on all of these tests are well within ATX specification.



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