Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the RM650's efficiency at low loads and at loads equal to 20%-110% of the PSU's maximum-rated load.



For a discussion of these results, see the text at the end of the previous page.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the RM650 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.


At low loads, the unit only operated in passive mode, putting out zero noise and scoring pretty high efficiency readings on all four tests. What is noteworthy here is that it achieved over 80% efficiency with only 40 W load, which will save you some money if you have your system sitting at idle or very low utilization for prolonged periods of time.

Corsair Link Screenshots

We took some screenshots of the Corsair Link software during the above tests. The order of screenshots is the same as the order of tests in the above table (test#1 to #4).

5VSB Efficiency

The ATX spec 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 circuit clearly performed above average and would have been in the high-performance league had it managed to score over 80% efficiency. You see, 80% efficiency for normal rails may be low for nowadays' standards, but is still very high for 5VSB as only very few 5VSB circuits score more.

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).


Phantom power was actually much lower than the 0.5 W limit of the ErP Lot 6 2013 directive.

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 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). Background noise inside the anechoic chamber was below 30 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 was in this case between 28°C and 30°C.



The RM650 features a generally silent operation, though it isn't as quiet as its bigger brothers, the RM750 and RM850. However, the latter are dangerously quiet since both miss the appropriate heatsinks for a passive operation, and the top-quality caps, and their fans engage rather late, which may cause the mediocre electrolytic caps in the secondary side to fail prematurely. We prefer the noisier but much safer operation of the RM650 unit since it ensures the unit's reliability in the long run.