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be quiet! Pure Power 11 700W PSU Review


Our efficiency testing procedure is detailed here.
Using results from the previous page, we plotted a chart showing the L11-CM-700’s efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.

The efficiency levels are pretty high under both light and normal loads. The ACRF topology indeed delivers what FSP and be quiet! promises, in this section at least.

Efficiency At Low Loads

In the following tests, we measure the L11-CM-700’s efficiency at loads significantly lower than 10 percent of its maximum capacity (the lowest load the 80 PLUS standard measures). The loads we dial are 20, 40, 60, and 80W. This is important for representing when a PC is idle, with power-saving features turned on.

Test # 12V 5V 3.3V 5VSB DC/AC (Watts) Efficiency Fan Speed (RPM) PSU Noise (dB[A]) PF/AC Volts
1 1.195A 0.497A 0.472A 0.196A 19.575 70.727% 677 11.5 0.836
12.112V 5.035V 3.391V 5.100V 27.677 115.05V
2 2.453A 0.994A 0.972A 0.393A 39.992 81.845% 681 12.4 0.885
12.107V 5.030V 3.387V 5.093V 48.863 115.04V
3 3.636A 1.491A 1.446A 5.087A 59.410 85.605% 682 12.4 0.906
12.104V 5.030V 3.387V 5.087V 69.400 115.05V
4 4.896A 1.987A 1.949A 0.787A 79.824 87.568% 684 12.5 0.922
12.100V 5.026V 3.385V 5.080V 91.157 115.05V

The fan spins at very low speeds and the unit’s efficiency is high during all four light load tests that we conduct.

5VSB Efficiency

The ATX specification (revision 1.4), along with CEC, ErP Lot 3 2014 and ErP Lot 6 2010/2013, states that the 5VSB standby supply efficiency should be as high as possible, recommending 75 percent or higher with 550mA, 1A, and 1.5A of load.

The supply should also achieve higher than 75% efficiency at 5VSB under full load, or with 3A if its max current output on this rail is higher than 3A.

We take six measurements: one each at 100, 250, 550, 1000, and 1500mA, and one with the full load the 5VSB rail can handle.

Test # 5VSB DC/AC
Efficiency PF/AC Volts
1 0.100A 0.510 73.066% 0.124
5.101V 0.698 115.05V
2 0.250A 1.275 78.413% 0.233
5.098V 1.626 115.05V
3 0.550A 2.801 79.393% 0.329
5.092V 3.528 115.05V
4 1.000A 5.083 78.490% 0.382
5.082V 6.476 115.06V
5 1.500A 7.609 80.553% 0.408
5.072V 9.446 115.05V
6 3.000A 15.122 78.642% 0.453
5.040V 19.229 115.06V

Satisfactory efficiency from the 5VSB circuit, however we know that FSP can do better here. Obviously its engineers avoided using a more advanced circuit, to keep the production cost under control.

Power Consumption In Idle And Standby

In the table below, you’ll find the power consumption and voltage values of all rails (except -12V) when the PSU is idle (powered on, but without any load on its rails), and the power consumption when the unit is in standby mode (without any load, at 5VSB).

Mode 12V 5V 3.3V 5VSB Watts PF/AC Volts
Idle 12.116V 5.048V 3.396V 5.104V 7.952 0.667
Standby 0.100 0.020

The vampire power is increased with both 115V and 230V input.

Fan RPM, Delta Temperature, And Output Noise

Our mixed noise testing is described in detail here.

The first chart below illustrates the cooling fan’s speed (in RPM), and the delta between input and output temperature. The results were obtained at 37°C (98.6°F) to 47°C (116.6°F) ambient temperature.

The next chart shows the cooling fan’s speed (again, in RPM) and output noise. We measure acoustics from one meter away, inside a hemi-anechoic chamber. Background noise inside the chamber is below 6 dB(A) during testing (it’s actually much lower, but our sound meter’s microphone hits its floor), and the results are obtained with the PSU operating at 37°C (98.6°F) to 47°C (116.6°F) ambient temperature.

The following graph illustrates the fan’s output noise over the PSU’s operating range. The same conditions of the above graph apply to our measurements, though the ambient temperature is between 30°C (86°F) to 32°C (89.6°F).

The PSU’s noise is low, throughout its entire operation range. Up to 440W the acoustics noise is within the 10-15 dB(A) range, while in the worst case scenario we measure less than 30 dB(A).

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