Efficiency

Using the efficiency results from the previous page, we plotted a chart that shows the CAPSTON_100-M's efficiency at low loads and at loads equal to 20%-100% of the PSU's maximum-rated load.



As it is clearly shown in the above graphs, this platform cannot meet the newest units in terms of efficiency, but does, on the other hand, cost less.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the CAPSTONE-1000-M 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, the Capstone delivered good efficiency. It even managed to stay well above 70% with 40 W, the lowest load we use in these tests.

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.


This rail didn't do too well in terms of efficiency. Its performance was far below the 80% mark in the last two tests and it failed to meet the efficiency levels the ATX spec sets in the first two tests.

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).


With a power consumption of nearly 0.5 W in standby, the unit barely managed to meet the ErP Lot 6 2013 directive. However, this was to be expected given this directive wasn't in effect when the series was first introduced.

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 level at a distance of 1 meter, 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°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 temperature was in-between 28°C and 30°C.



The large Capstone unit doesn't even feature a quiet operation under normal conditions. Semi-passive PSUs weren't terribly popular when it was introduced because efficiency levels weren't as high as in today's PSUs, so manufacturers focused on a unit's reliability instead of its noise output.