Efficiency

Using the efficiency results from the previous page, we plotted a chart showing efficiency of the RM650i at low loads and at loads equal to 20% -100% of the PSU's maximum-rated load.



Efficiency is very high with normal loads and somewhere around the middle of the pack with light loads. We would like to see better results with light loads.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the RM650i at loads 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.

The fan doesn't spin at all with light loads. Efficiency dropped below 80% in the 20% load test, but stayed well above the 80% mark in all other tests.

Corsair Link Screenshots

Screenshots of the Corsair Link software follow. The order of these screenshots is the same as the order of the tests shown in the table above (low loads efficiency test #1 to test #4).



The readings were only accurate in the second test. Don't count on getting an accurate reading in Corsair Link at light loads.

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.

We were left quite satisfied by the 5VSB rail since at least one efficiency reading exceeded 80%. Efficiency on this rail will be even higher with 115VAC input.

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 values when the PSU is in standby mode (without any load at 5VSB).

Vampire power is very low.

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 38-47 °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 38-47 °C ambient.



The following graphs illustrate the fan's output noise and speed 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 RM650i is very quiet, especially under normal operating conditions. This unit should be on your short list if you want to build a quiet system and 650W is enough.


As you can see in the graph above, the fan's speed is kept very low. Very rarely will the fan exceed 1000 RPM if operating temperatures are kept below 30 °C.