Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the efficiency of the L8-500W at low loads and at loads equal to 20-110% of the PSU's maximum-rated load.



Efficiency at low loads was always pretty good for a Bronze unit and satisfactory at normal loads with an average performance for the category.

Efficiency at Low Loads

The next tests measure the efficiency of the L8-500W at loads much lower than 20% of its maximum-rated load (the lowest load that the 80 Plus Standard measures). The loads that we dialed were 40-, 60-, 80-, and 90 W. This is important for settings where the PC is in idle mode with power saving turned on.


Efficiency at low loads is high enough since its small capacity allows the PSU to operate more efficiently with loads below 100 W. The most impressive fact here is the ultra-silent fan that spun at very low speeds, generating minimal amounts noise. Be Quiet!'s PURE POWER L8 500 W really managed to honor the "Quiet!" in its name.

5VSB Efficiency

The ATX spec states that the 5VSB standby supply's efficiency should be as high as possible and recommends 50% or higher efficiency with 100 mA of load, 60% or higher with 250 mA of load, and 70% or higher with 1 A or more of load.

We will take four measurements: one at 100, 250, and 1000 mA each, and one with the full load that the 5VSB rail can handle.


Efficiency is quite good in the first two tests and within normal levels in the last two tests.

Power Consumption in Idle & Standby

The table below has the power consumption and voltage values of all rails (except -12V) when the PSU is in idle mode (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).


The power that the unit consumes during standby is minimal--close to one third of the limit that the ErP Lot 6 2013 directive sets. This is good for both the environment and your wallet.

Fan RPM, Delta Temperature and Output Noise

The cooling fan's speed (RPMs) and the delta difference between input and output temperature are illustrated in the following chart. The following results were obtained at 39-45°C ambient.



A chart that shows the cooling fan's speed (RPMs) and the output noise follows. We measure the fan's noise from 1 meter away and inside a small custom-made anechoic chamber whose internals are completely covered in specialized soundproofing material (Be Quiet! Noise Absorber Kit). The background noise inside the anechoic chamber was below 29 dBA during testing and the results were obtained with the PSU operating at and ambient of 39-45°C.



The following graph illustrates the fan's output noise throughout the entire operating range of the PSU. The same conditions of the above graph apply to our measurements, but the ambient in this case was between 28 and 30°C.



This is the quietest normal (not fanless) PSU we have ever tested. Be Quiet! did a hell of a job in this area.