Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the efficiency of the SF650P14PE at low loads and at loads equal to 20% -100% of the PSU's maximum-rated load.



The Platinum King unit scores second in the charts above, losing out to only the extraordinary and much more expensive Seasonic Prime unit. This unit's native cables surely play a significant role with its increased efficiency levels, especially at high loads.

Efficiency at Low Loads

We measured the efficiency of the SF650P14PE 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 a capacity over 500 W). This is important for settings where the PC is in idle mode with Power Saving turned on.

Efficiency is very high at light loads, but the fan could afford to spin slower for a much quieter operation.

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's efficiency is disappointing.

Power Consumption in Idle & Standby

In the table below, you will find 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 PSU's vampire power is higher than we had hoped for. With as much power consumption in standby, it is nearly impossible to achieve more than 45% efficiency with 0.045A at 5VSB, which is the threshold 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 39 °C - 46 °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 39 °C - 46 °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 above graph clearly shows that the SF-650P14PE could afford to operate significantly quieter by utilizing a more relaxed fan profile, especially at light and moderate loads. A semi-passive operation could also help.