Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the SS-1200XP3's efficiency at low loads and at loads equal to 20%-100% of the PSU's maximum-rated load.



Seasonic's new platform scored incredibly well with low loads, although it stayed behind Super Flower's fresh Platinum platform. However, with high loads, it scored second place, only losing to the Titanium Corsair AX1500i which costs about twice as much.

Efficiency at Low Loads

In the next tests, we measured the SS-1200XP3's efficiency 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 a capacity over 500 W). This is important for settings where the PC is in idle mode with Power Saving turned on.

At low loads, efficiency was pretty high for such a strong unit. Temperatures inside our hotbox were also high enough to nullify its passive operation with even low loads.

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 performed well enough; however, we would like its efficiency to be a little higher in the last test since it didn't manage to crack the 80% mark.

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 on 5VSB).

Less than 0.2 W power consumption at idle, so there is nothing more to ask for here.

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 37°C-46°C ambient.



A chart that shows the cooling fan's speed (RPMs) and the output noise follows. We measure the fan's output noise 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 37°C-46°C ambient.



The following graph illustrates the fan's output noise throughout the PSU's entire operating range. The same conditions as for the graph above apply to our measurements, but the ambient temperature was in-between 28°C and 30°C.



The unit was noisy overall because Seasonic uses a high-speed fan and a somewhat aggressive fan profile. As you can see in the above graph, its passive operation was restricted to around one fifth of the unit's operational range.