Efficiency

Using the efficiency results from the previous page, we plotted a chart to show the G2-850's efficiency at low loads and loads equal to 20%-110% of the PSU's maximum-rated load.



Take into account the PSU's large capacity and efficiency at low loads is quite high. The G2-850 also placed around the middle of the pack with normal loads, which is a very good position given we threw a few Platinum units into the mix.

Efficiency at Low Loads

In the next tests, we measured the efficiency of the G2-850 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.

Despite the high ambient inside our hot-box, the PSU finished all low-load tests without engaging its fan, so it was literally whisper quiet. Easily cracking the 80% mark during the second test and reaching 87% with 100 W, the unit also did quite well in terms of efficiency.

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.

The 5VSB rail wasn't that efficient and nor was its voltage regulation good, although voltage regulation on 5VSB isn't as important as on other rails. As stated in our reviews of similar Super Flower platforms, SF should upgrade the 5VSB circuit common to most of their platforms because it is the same 5VSB circuit as in models of the previous generation. Efficient 5VSB rails would crack 80% efficiency in both of the last two tests (1 A load and full load).

Power Consumption in Idle & Standby

In the table below, you will find every rail's power consumption and its voltage value (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 was a little higher than with other modern units, which is surely due to the 5VSB rail's low overall efficiency at, especially, low loads.

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 41°C-48°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 20 dBA during testing, and the results were obtained with the PSU operating at 41°C-48°C ambient.