Efficiency

Using the efficiency results from the previous page, we plotted a chart showing efficiency of the G550M at low loads and at loads equal to 20%-110% of the PSU's maximum-rated load.



At low loads, the G550M scored high efficiency and managed to get really close to Seasonic's Gold-certified G550 unit. It did well at normal loads, too, since it registered above 88% efficiency, which is currently the highest we have ever measured in a 550 W Bronze unit. CWT and Cooler Master did a fine job here.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the G550M at loads much lower than 20% of its maximum rated load (the lowest load that 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.


Efficiency at low loads is pretty high, especially if we take into account that this is a Bronze-certified PSU, not a Gold or Platinum one. In three out of the four low load tests, the G550M easily passed the 80% mark, reaching an impressive 87.3% with 100 W.

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 the 5VSB rail can handle.


The 5VSB registered decent overall efficiency, though we would like to see readings closer to 80% for the last two tests.

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).


In standby, power consumption was very low at 0.18 W, so the G550M easily meets the ErP Lot 6 2013 requirements.

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-46°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, 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 30 dBA during testing, and the results were obtained with the PSU operating at 38°C-46°C ambient.



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°C and 30°C.



As you can see in the above graph, this is a very silent PSU, especially at low- to mid-range loads.