EfficiencyUsing the efficiency results from the previous page, we plotted a chart showing the efficiency of the HCG-750M at low loads and at loads equal to 20-110% of the PSU's maximum-rated load.
Efficiency isn't that great at loads below 100 W and is in the normal range for units of the Bronze category with normal loads.
Efficiency at Low LoadsIn the next tests, we measured the efficiency of the HCG-750M 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 |
|Test #||12 V||5 V||3.3 V||5 VSB||Power|
|Efficiency||Fan Speed||Fan Noise||PF/AC |
|1||1.806A||1.962A||1.957A||0.196A||39.66W||71.41%||1018 RPM||37.7 dBA||0.810|
|2||3.367A||1.961A||1.959A||0.391A||59.72W||77.62%||1061 RPM||38.6 dBA||0.856|
|3||4.923A||1.962A||1.959A||0.585A||79.70W||80.91%||1193 RPM||40.3 dBA||0.882|
|4||6.482A||1.962A||1.960A||0.782A||99.72W||82.78%||1327 RPM||42.0 dBA||0.904|
Efficiency on these tests isn't so impressive, and we would like to see a 2-5% higher reading on all tests. Also, the fan increased its noise output to 42 dBA during the last test, so it wasn't as quiet as we would like at such low loads. Here, we should note that the ambient in which we conducted the above tests was within 35-37°C.
5VSB EfficiencyThe 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|
|Test #||5VSB||Power (DC/AC)||Efficiency||PF/AC Volts|
Efficiency at 5VSB is above the specified thresholds throughout all load ranges. However, the PSU has nothing exceptional to show in this area since efficiency failed to come even close to 80%.
Power Consumption in Idle & StandbyIn 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).
| Idle / Standby |
|Mode||12 V||5 V||3.3 V||5VSB||Power (AC)||PF/AC Volts|
Vampire power is very low and the unit easily meets the ErP Lot 6 2013 requirements.
Fan RPM, Delta Temperature and Output NoiseThe 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- 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 and inside a custom-made anechoic chamber that is completely covered in specialized soundproofing material (Be Quiet! Noise Absorber Kit) internally. Background noise inside the anechoic chamber was below 30 dBA during testing and the results were obtained with the PSU operating at 38-45°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 in this case was between 28 and 30°C.