Efficiency

Using the efficiency results from the previous page, we plotted a chart that shows how efficient the PSU is at low loads and loads equal to 20%-100% of its maximum-rated load.



The V550 managed to be just as incredibly efficient as the VSM550's at light loads, which puts even the best Platinum units of similar capacity to shame. With normal loads, efficiency was quite high as well, though notably less so than with the VSM550.

Efficiency at Low Loads

The next tests measure the V550's efficiency at loads that are much lower than 20% of its maximum-rated load (the lowest load the 80 Plus Standard measures). The loads we dialed were 40 W, 60 W, 80 W, and 100 W (for PSUs with over 500 W of capacity). This is important for settings where the PC is in idle mode with Power Saving turned on.


This PSU plays ball in its own league at light loads, scoring extremely high efficiency levels. We also make a point of applying high ambient temperatures in these tests (33-38°C), which only had the fan spin slowly, producing nearly no noise.

5VSB Efficiency

The ATX specification states that 5VSB standby supply 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 the 5VSB rail can handle.


Load regulation on the 5VSB rail was great, and it proved to be very efficient. We are usually left very satisfied when we see readings above 80% in these tests, and our software measured 80.7% efficiency at full load.

Power Consumption in Idle & Standby

In the table below, you will find the power consumption and the 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).


Vampire power was very low with 230VAC, which helps the 5VSB rail achieve such high efficiency with light loads.

Fan RPM, Delta Temperature & 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 38°C-45°C ambient.



A chart that shows the cooling fan's speed (RPMs) and output noise follows. We measure the fan's noise from one meter away, inside a small custom-made anechoic chamber whose internals are completely covered in specialized soundproofing material (Be Quiet! Noise Absorber Kit). Background noise inside the anechoic chamber was below 20 dBA during testing, and the results were obtained with the PSU operating at 38°C-45°C ambient.



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



The fan spun at very low speeds at up to 320 W, which resulted in around 28 dBA. Only after 480 W did noise exceeded 40 dBA, reaching 47 dBA for a very short period of time at worst. Overall, this is a silent PSU that must be pushed hard in a sub-par environment to produce a lot of noise.