Efficiency

Using the efficiency results from the previous page, we plotted a chart for the V650's efficiency at low loads and at loads equal to 20%-100% of the PSU's maximum-rated load.



We expected efficiency with light loads to be better given the amazing results the older VSM550 and fresh V550 units achieved. However, you can't call an average of 85% efficiency at light loads bad, although some Gold-certified platforms with a similar capacity are even more efficient. The V650 performed better at normal loads, staying closer to the high-end competition and beating out many other Gold-certified units.

Efficiency at Low Loads

We measured the V650's efficiency at loads much lower than 20% of its maximum-rated load (the lowest load the 80 Plus Standard measures) in these tests. 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.


At light loads, efficiency is high; however, there is no competing with the V550 that cracked 90% efficiency in the last three tests. The capacity difference between the V550 and V650 might only be 100 W, but the smaller model performs much better at light loads, which puts its bigger brother to shame.

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.


The 5VSB rail isn't that efficient since it barely failed to crack the 80% mark in even the last test.

Power Consumption in Idle & Standby

In the table below, you will find the power consumption and voltage values of the rails (except for -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).


As per usual, power consumption is very low in standby, lower than the maximum the ErP Lot 6 2013 directive sets.

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 38-45 °C ambient.



A chart that shows the cooling fan's speed (RPMs) and its 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 38-45 °C ambient.



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



At normal ambient temperatures, the PSU's fan is inaudible unless you have incredibly good ears. Clearly, its fan profile is tuned for operating temperatures below 40 °C since the V650 is supposed to deliver its full power continuously at up to 40 °C.