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Efficiency, Temperature And Noise
Efficiency
Our efficiency testing procedure is detailed here.
Using the results from the previous page, we plotted a chart showing the L9-CM-600W's efficiency at low loads, and loads from 10 to 110 percent of the PSU's maximum-rated capacity.
be quiet!'s latest lands right between the Gold and Bronze units on the average efficiency graph under normal loads, while it passes the Gold-rated Seasonic unit under light loads.
Efficiency At Low Loads
In the following tests, we measure the efficiency of be quiet!'s L9-CM-600W at loads significantly lower than 10 percent of its maximum capacity (the lowest load the 80 PLUS standard measures). The loads we dialed were 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) | Fan Noise | PF/AC Volts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.194A | 0.491A | 0.474A | 0.196A | 19.61 | 74.91% | 565 | 17.5 dB(A) | 0.764 |
| 12.200V | 5.016V | 3.365V | 5.037V | 26.18 | 115.1V | ||||
| 2 | 2.422A | 0.988A | 0.979A | 0.396A | 39.74 | 85.63% | 565 | 17.5 dB(A) | 0.786 |
| 12.184V | 5.012V | 3.361V | 5.030V | 46.41 | 115.1V | ||||
| 3 | 3.664A | 1.486A | 1.488A | 5.021A | 59.85 | 86.21% | 565 | 17.5 dB(A) | 0.967 |
| 12.119V | 5.028V | 3.356V | 5.021V | 69.42 | 115.1V | ||||
| 4 | 4.885A | 1.994A | 1.967A | 0.796A | 79.80 | 87.75% | 565 | 17.5 dB(A) | 0.972 |
| 12.120V | 5.020V | 3.352V | 5.013V | 90.94 | 115.0V |
Under light loads, efficiency is high overall, especially if we take into account that this is a Silver-rated unit. The fan is completely inaudible during these tests.
5VSB Efficiency
The ATX specification states that 5VSB standby supply efficiency should be as high as possible, recommending 50 percent or higher with 100mA of load, 60 percent or higher with 250mA of load and 70 percent or higher with 1A or more of load.
We take four measurements: one each at 100, 250 and 1000mA, and one with the full load the 5VSB rail can handle.
| Test # | 5VSB | DC/AC (Watts) | Efficiency | PF/AC Volts |
|---|---|---|---|---|
| 1 | 0.102A | 0.51 | 70.83% | 0.126 |
| 5.048V | 0.72 | 115.1V | ||
| 2 | 0.252A | 1.27 | 74.27% | 0.232 |
| 5.045V | 1.71 | 115.1V | ||
| 3 | 1.002A | 5.04 | 72.62% | 0.349 |
| 5.027V | 6.94 | 115.1V | ||
| 4 | 3.002A | 14.95 | 72.43% | 0.401 |
| 4.981V | 20.64 | 115.1V |
It's a shame that the 5VSB rail's efficiency is so low. Most likely the lack of a proper PWM controller is to blame.
Power Consumption In Idle And Standby
| Mode | 12V | 5V | 3.3V | 5VSB | Watts | PF/AC Volts |
|---|---|---|---|---|---|---|
| Idle | 12.173V | 5.045V | 3.367V | 5.054V | 6.06 | 0.402 |
| 115.1V | ||||||
| Standby | 0.10 | 0.018 | ||||
| 115.1V |
In the table above, 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 PSU is in standby mode (without any load, at 5VSB).
Power consumption in standby is low, however this isn't enough to allow for high efficiency at 5VSB.
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 34 °C (93.2 °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 measured acoustics from one meter away, inside a small, custom-made anechoic chamber with internals completely covered in sound-proofing material (be quiet! Noise Absorber kit). Background noise inside the chamber was below 18 dB(A) during testing, and the results were obtained with the PSU operating at 36 °C (93.2 °F) to 45 °C (116.6 °F) ambient temperature.
The following graph illustrates the fan's output over the entire operating range of the PSU. The same conditions of the above graph apply to our measurements, though the ambient temperature was between at 28 °C (82.4 °F) to 30 °C (86 °F).
Up to around 450W, this PSU is almost inaudible. Under higher loads, you will be able to hear it if you're up close.
