Efficiency

Using the efficiency results from the previous page, we plotted a chart showing efficiency of the HCG-850 at low loads and at loads equal to 20-110% of the PSU's maximum-rated load.



At low loads, the HCG-850 M achieved a higher overall efficiency than its smaller brother. It should actually be the other way around. The HCG-850 M also takes the lead at normal loads. The higher overall efficiency of the HCG-850M compared to its smaller brother is a result of the more efficient main switchers used and the additional SBRs that rectify its +12V rail.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the HCG-850 at loads much lower than 20% of its maximum-rated load (the lowest load that the 80 Plus Standard measures). The loads that we dialed were 40-, 60-, 80-, 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.


Efficiency at low loads is good enough for a Bronze 850 W unit. Also, the fan surely made its presence felt but wasn't annoying, at least to our ears.

5VSB Efficiency

The ATX spec states that the 5VSB standby supply's 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 that the 5VSB rail can handle.


5VSB efficiency is average for the category--nothing exciting, but nor is it bad. We consider anything over 80% with a full load a high-efficiency reading on this rail. If the unit reaches or exceeds the aforementioned mark with a 1 A load at 5VSB, it is performing exceptionally well in this area.

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).


Like all units that use a modern, dedicated PWM standby controller, this one too registers very low phantom power, something to benefit the environment and your pocket.

Fan RPM, Delta Temperature and 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 39-46°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 totally covered in specialized soundproofing material (Be Quiet! Noise Absorber Kit). The background noise inside the anechoic chamber was below 30 dBA during testing, and the results were obtained with the PSU operating at 39-46°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 in this case was between 28 and 30°C.



At normal ambient, the fan profile of this unit is more relaxed than that of the HCG-750M.