Seasonic Focus SPX Series 750 W SFX PSU Review

Name: Seasonic Focus SPX Series 750 W SFX PSU
Brand: Seasonic
Price: 200 USD

crmaris

on Mar 11th, 2022,

in Power Supplies.

Manufacturer: Seasonic

Fan Noise »

Efficiency

Using the results we gathered so far, we plotted a chart showing the PSU's efficiency at low loads and loads ranging from 10 to 110 percent of the maximum-rated capacity.

Efficiency is high for all load ranges, but still worse for all but 2% load compared to the SF750.

10%–110% Load Testing

These tests reveal the PSU's load regulation and efficiency levels under high ambient temperatures and show how the fan-speed profile behaves under harsh operating conditions.

Load Regulation & Efficiency Testing Data - Seasonic Focus SPX-750
Test	12V	5V	3.3V	5VSB	Power (DC/AC)	Efficiency	Fan Speed	PSU Noise	Temp (In/Out)	PF/AC Volts
10%	4.372A	1.99A	1.977A	0.984A	74.987W	87.087%	1114 RPM	19.4 dB(A)	40.63°C	0.756
10%	12.214V	5.025V	3.337V	5.08V	86.106W	87.087%	1114 RPM	19.4 dB(A)	45.69°C	230.28V
20%	9.756A	2.986A	2.968A	1.184A	149.931W	91.802%	1140 RPM	20.0 dB(A)	41.11°C	0.885
20%	12.202V	5.023V	3.335V	5.066V	163.321W	91.802%	1140 RPM	20.0 dB(A)	46.59°C	230.32V
30%	15.491A	3.485A	3.465A	1.384A	224.895W	93.201%	1093 RPM	19.1 dB(A)	41.74°C	0.927
30%	12.191V	5.021V	3.332V	5.059V	241.302W	93.201%	1093 RPM	19.1 dB(A)	47.51°C	230.27V
40%	21.224A	3.987A	3.963A	1.585A	299.971W	93.311%	1950 RPM	36.5 dB(A)	42.12°C	0.943
40%	12.192V	5.017V	3.33V	5.047V	321.476W	93.311%	1950 RPM	36.5 dB(A)	48.18°C	230.28V
50%	26.563A	4.987A	4.959A	1.788A	374.358W	93.412%	1113 RPM	19.4 dB(A)	42.21°C	0.951
50%	12.192V	5.013V	3.327V	5.035V	400.758W	93.412%	1113 RPM	19.4 dB(A)	48.77°C	230.33V
60%	31.922A	5.985A	5.956A	1.991A	449.268W	93.148%	1642 RPM	31.7 dB(A)	42.71°C	0.956
60%	12.200V	5.013V	3.324V	5.022V	482.314W	93.148%	1642 RPM	31.7 dB(A)	49.88°C	230.33V
70%	37.302A	6.989A	6.954A	2.193A	524.054W	92.912%	1639 RPM	31.3 dB(A)	43.53°C	0.961
70%	12.197V	5.009V	3.322V	5.013V	564.034W	92.912%	1639 RPM	31.3 dB(A)	51.31°C	230.32V
80%	42.703A	7.987A	7.95A	2.299A	599.3W	92.475%	2215 RPM	40.6 dB(A)	44.04°C	0.963
80%	12.210V	5.01V	3.319V	5.001V	648.066W	92.475%	2215 RPM	40.6 dB(A)	52.3°C	230.32V
90%	48.449A	8.484A	8.438A	2.404A	674.329W	91.795%	2993 RPM	49.3 dB(A)	45.03°C	0.965
90%	12.216V	5.008V	3.317V	4.99V	734.605W	91.795%	2993 RPM	49.3 dB(A)	54.31°C	230.32V
100%	53.993A	8.986A	8.956A	3.02A	749.547W	91.061%	3482 RPM	52.4 dB(A)	45.67°C	0.967
100%	12.221V	5.007V	3.315V	4.965V	823.127W	91.061%	3482 RPM	52.4 dB(A)	55.91°C	230.31V
110%	59.400A	9.987A	10.049A	3.025A	824.562W	90.537%	3506 RPM	53 dB(A)	46.66°C	0.968
110%	12.227V	5.006V	3.312V	4.958V	910.752W	90.537%	3506 RPM	53 dB(A)	57.54°C	230.31V
CL1	0.113A	15.593A	15.526A	0A	131.265W	86.393%	2335 RPM	42.9 dB(A)	42.98°C	0.875
CL1	12.212V	5.021V	3.323V	5.089V	151.939W	86.393%	2335 RPM	42.9 dB(A)	48.57°C	230.32V
CL2	0.113A	19.916A	0A	0A	101.375W	84.35%	2716 RPM	45.6 dB(A)	40.92°C	0.836
CL2	12.201V	5.021V	3.33V	5.101V	120.184W	84.35%	2716 RPM	45.6 dB(A)	48.34°C	230.32V
CL3	0.112A	0A	19.818A	0A	67.361W	79.693%	2159 RPM	42.2 dB(A)	40.51°C	0.744
CL3	12.210V	5.021V	3.33V	5.1V	84.527W	79.693%	2159 RPM	42.2 dB(A)	49.77°C	230.32V
CL4	61.294A	0A	0A	0A	749.485W	92.051%	3532 RPM	53.1 dB(A)	45.96°C	0.967
CL4	12.227V	5.014V	3.325V	5.067V	814.214W	92.051%	3532 RPM	53.1 dB(A)	56.13°C	230.31V

This PSU delivers its full power without any issues under harsh operating conditions. Don't expect its small fan to stay quiet, though.

Light-Load Testing

We measure the PSU's efficiency at loads significantly lower than 10 percent of the maximum capacity—the lowest load the 80 PLUS standard measures. This is important for when a PC is idle with its power-saving features turned on.

Light Load Efficiency - Seasonic Focus SPX-750
Test	12V	5V	3.3V	5VSB	Power (DC/AC)	Efficiency	Fan Speed	PSU Noise	Temp (In/Out)	PF/AC Volts
20W	1.223A	0.497A	0.494A	0.196A	19.984W	76.412%	0 RPM	<6.0 dB(A)	39.73°C	0.443
20W	12.128V	5.025V	3.341V	5.109V	26.157W	76.412%	0 RPM	<6.0 dB(A)	36.6°C	230.28V
40W	2.675A	0.696A	0.691A	0.294A	39.985W	78.058%	0 RPM	<6.0 dB(A)	40.97°C	0.61
40W	12.216V	5.025V	3.34V	5.104V	51.225W	78.058%	0 RPM	<6.0 dB(A)	37.55°C	230.28V
60W	4.137A	0.895A	0.889A	0.392A	59.984W	86.164%	0 RPM	<6.0 dB(A)	42.57°C	0.697
60W	12.211V	5.026V	3.339V	5.1V	69.617W	86.164%	0 RPM	<6.0 dB(A)	38.73°C	230.28V
80W	5.592A	1.094A	1.087A	0.49A	79.922W	88.494%	0 RPM	<6.0 dB(A)	44.11°C	0.769
80W	12.214V	5.026V	3.339V	5.095V	90.313W	88.494%	0 RPM	<6.0 dB(A)	39.83°C	230.28V

I would like to see over 80% efficiency with 40 W load.

Super-Light Load Testing

We measure the PSU's efficiency with a 10 W load if its maximum power is 500 W or less in the following tests. If the PSU is stronger, we apply 2% of its maximum-rated-capacity load.

Super-Light Load Efficiency - Seasonic Focus SPX-750
12V	5V	3.3V	5VSB	Power (DC/AC)	Efficiency	Fan Speed	PSU Noise	Temp (In/Out)	PF/AC Volts
1.047A	0.264A	0.264A	0.051A	15.152W	73.725%	0 RPM	<6.0 dB(A)	24.39°C	0.66
12.116V	5.017V	3.341V	5.117V	20.552W	73.725%	0 RPM	<6.0 dB(A)	21.35°C	115.12V

The PSU easily breaks the 70% mark with 2% load.

5VSB Efficiency

5VSB Efficiency - Seasonic Focus SPX-750
Test #	5VSB	Power (DC/AC)	Efficiency	PF/AC Volts
1	0.1A	0.512W	62.964%	0.032
1	5.117V	0.813W	62.964%	230.31V
2	0.25A	1.278W	72.615%	0.068
2	5.112V	1.76W	72.615%	230.33V
3	0.55A	2.807W	76.075%	0.134
3	5.104V	3.69W	76.075%	230.33V
4	1A	5.091W	77.336%	0.212
4	5.091V	6.583W	77.336%	230.33V
5	1.5A	7.614W	77.689%	0.272
5	5.076V	9.801W	77.689%	230.33V
6	2.999A	15.096W	77.499%	0.364
6	5.033V	19.479W	77.499%	230.33V

The 5VSB rail is inefficient.

Power Consumption in Idle and Standby

Idle / Standby - Seasonic Focus SPX-750
Mode	12V	5V	3.3V	5VSB	Power (AC)	PF/AC Volts
Idle	12.114V	5.017V	3.342V	5.12V	3.142W	0.223
Idle	12.114V	5.017V	3.342V	5.12V	3.142W	115.1V
Standby					0.072W	0.009
Standby					0.072W	115.1V