Seasonic PRIME Series 750 W Review 22

Seasonic PRIME Series 750 W Review

Cross Load Tests »

Efficiency

Using the efficiency results from the previous page, we plotted a chart showing the efficiency of the SSR-750TD at low loads and at loads equal to 20%-100% of the PSU's maximum-rated load.



The Prime 750 easily destroys the competition at both light and normal loads. This platform sets new standards in the Titanium category, it really is as simple as that. If EVGA or Super Flower had sent us a Titanium 750 W unit (either the SuperNOVA 750 T2 or its corresponding SF model) for evaluation, we would have included it in our charts in order to offer you a direct point of comparison to the SSR-750TD.

Efficiency at Low Loads

In these next tests, we measured the efficiency of the SSR-750TD 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 - Seasonic SSR-750TD
Test #12 V5 V3.3 V5 VSBPower
(DC/AC)
EfficiencyFan SpeedFan NoisePF/AC
Volts
12.847A0.492A0.475A0.194A39.75W88.47%0 RPM0 dB(A)0.651
12.182V5.066V3.354V5.061V44.93W230.3V
24.062A0.980A0.982A0.394A59.72W91.34%0 RPM0 dB(A)230.3
12.180V5.065V3.352V5.055V65.38W230.3V
35.285A1.476A1.489A0.589A79.81W92.72%0 RPM0 dB(A)0.794
12.179V5.065V3.354V5.052V86.08W230.3V
46.502A1.974A1.965A0.789A99.75W93.61%0 RPM0 dB(A)0.832
12.178V5.065V3.354V5.047V106.56W230.3V
Efficiency with light loads is super high. This truly is a Titanium platform, there isn't even the slightest doubt about that. Even with only 40 W load, the PSU scores above 88% efficiency, and it easily surpassing the 90% mark with higher 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.

5VSB Efficiency - Seasonic SSR-750TD
Test #5VSBPower (DC/AC)EfficiencyPF/AC Volts
10.101A0.51W69.86%0.024
5.010V0.73W230.3V
20.251A1.26W74.56%0.056
5.004V1.69W230.3V
31.002A4.98W79.05%0.180
4.971V6.30W230.3V
43.001A14.66W78.52%0.336
4.885V18.67W230.3V
The 5VSB rail offers decent performance, but its performance isn't top-notch, like that of its other rails. Seasonic should probably look into this in order to increase this rail's performance in an attempt to bring it up to the levels of its other rails.

Power Consumption in Idle & Standby

In the table below, you will find the power consumption and 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 - Seasonic SSR-750TD
Mode12 V5 V3.3 V5VSBPower (AC)PF/AC Volts
Idle12.185V5.067V3.353V5.067V3.70W0.116
230.3V
Standby0.09W0.003
230.3V

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 40 °C - 46 °C ambient.



A chart that shows the cooling fan's speed (RPMs) and its output noise follows. We measure the fan's noise from one 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 40 °C - 46 °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 temperature was in-between 28 °C and 30 °C.



The fan's passive operation lasts until around 300 W of load, and it spins at very low speeds afterward, making it very quiet.
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