Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the Tachyon-750's efficiency at low loads and loads equal to 20%-110% of the PSU's maximum-rated load.



Efficiency at low loads is high, easily competing with other Platinum units, and the same applies to normal load results. The gap to new Platinum units by the competition is significant, though. The age of SF's older platform definitely shows in these tests.

Efficiency at Low Loads

The next tests measure the efficiency of the Tachyon-750 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.


Efficiency at low loads was pretty high. This PSU will save you lots of money if your system idles at such low loads and you keep it at idle for long periods of time.

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.


With only 2.5 A maximum current output and somewhat low efficiency, the 5VSB circuit isn't one of the unit's strong points.

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).


While vampire power is increased, it is still under the 0.5 W limit, which makes the Tachyon-750 ErP Lot 6 2013 compliant.

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 39°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). The background noise inside the anechoic chamber was below 30 dBA during testing, and the results were obtained with the PSU operating at 39°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 in this case was between 28°C and 30°C.



The above graph illustrates the Tachyon-750's quiet operation very nicely. Noise-sensitive users will definitely appreciate its low noise levels.