Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the CS650M's efficiency at low loads and loads equal to 20%-110% of the PSU's maximum-rated load.



The CS650M performed incredibly well, which earned it the top spot in the above graphs comparing it to units with roughly the same capacity. Its modern design apparently played a crucial role here since the resonant converter it utilizes dramatically restricts energy losses.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the CS650M 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.

At low loads, efficiency was simply impressive since the unit easily managed to surpass the 80% efficiency mark on all tests. Great Wall and Corsair did a fine job in this area.

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 rail is highly efficient since it managed to pass the for this rail harder of the two tests with a score of 80%.

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).

Vampire power is kept at normal levels for an ErP Lot 6 2013 compliant PSU.

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 entire operating range of the PSU. The same conditions of the above graph apply to our measurements, but the ambient was in this case between 26°C and 29°C.



The unit was really quiet under normal conditions since its fan kept RPMs low at even the highest possible load this PSU can handle. The fan's profile is optimized to have it operate silently, and the CS650M is solid proof that a PSU doesn't have to feature a semi-fanless operation to be silent enough for even noise-sensitive users.