Corsair CX550F RGB Power Supply Review

The CX550F is one of the few Corsair PSUs with RGB lighting.

Corsair CX550F RGB
(Image: © Tom's Hardware)

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Primary Rails And 5VSB Load Regulation

The following charts show the main rails' voltage values recorded between a range of 40W up to the PSU's maximum specified load, along with the deviation (in percent). Tight regulation is an important consideration every time we review a power supply, because it facilitates constant voltage levels despite varying loads. Tight load regulation also, among other factors, improves the system's stability, especially under overclocked conditions. At the same time, it applies less stress to the DC-DC converters that many system components utilize.

Load regulation is loose on all rails. 

Hold-Up Time

Simply put; hold-up time is the amount of time that the system can continue to run without shutting down or rebooting during a power interruption.

The hold-up time is a bit lower than 17ms, and the power ok signal doesn't reach 16ms. 

Inrush Current

Inrush current, or switch-on surge, refers to the maximum, instantaneous input current drawn by an electrical device when it is first turned on. A large enough inrush current can cause circuit breakers and fuses to trip. It can also damage switches, relays, and bridge rectifiers. As a result, the lower the inrush current of a PSU right as it is turned on, the better.

Inrush current is at normal levels with 115V and on the high side with 230V. 

Leakage Current

In layman's terms, leakage current is the unwanted energy transfer from one circuit to another. In power supplies, it is the current flowing from the primary side to the ground or the chassis, which in most cases is connected to the ground. We use a GW Instek GPT-9904 electrical safety tester instrument to measure leakage current.

The leakage current test is conducted at 110% of the DUT's rated voltage input (so for a 230-240V device, we should conduct the test with 253-264V input). The maximum acceptable limit of a leakage current is 3.5 mA. The IEC-60950-1 regulation defines it as ensuring that the current is low and will not harm any person coming in contact with the power supply's chassis.

Corsair CX550F

(Image credit: Tom's Hardware)

Leakage current is dead low. 

10-110% Load Tests

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

Swipe to scroll horizontally
Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])Temps (In/Out)PF/AC Volts
12.749A1.979A1.983A0.997A54.95483.695%61210.740.39°C0.976
Row 2 - Cell 0 12.132V5.053V3.329V5.016V65.660Row 2 - Cell 6 Row 2 - Cell 7 Row 2 - Cell 8 45.53°C115.15V
26.535A2.978A2.981A1.199A110.01288.042%63211.940.59°C0.976
Row 4 - Cell 0 12.106V5.038V3.320V5.003V124.954Row 4 - Cell 6 Row 4 - Cell 7 Row 4 - Cell 8 46.49°C115.15V
310.670A3.482A3.488A1.403A165.00389.304%67416.041.53°C0.979
Row 6 - Cell 0 12.085V5.027V3.312V4.990V184.765Row 6 - Cell 6 Row 6 - Cell 7 Row 6 - Cell 8 47.88°C115.15V
414.821A3.988A3.993A1.607A220.00189.561%73317.041.68°C0.985
Row 8 - Cell 0 12.064V5.016V3.305V4.978V245.644Row 8 - Cell 6 Row 8 - Cell 7 Row 8 - Cell 8 48.64°C115.15V
518.643A5.001A5.008A1.813A274.98989.270%81022.242.25°C0.989
Row 10 - Cell 0 12.041V5.000V3.296V4.963V308.043Row 10 - Cell 6 Row 10 - Cell 7 Row 10 - Cell 8 50.44°C115.15V
622.480A6.021A6.026A2.000A329.87988.670%92125.743.06°C0.989
Row 12 - Cell 0 12.018V4.984V3.287V4.949V372.030Row 12 - Cell 6 Row 12 - Cell 7 Row 12 - Cell 8 52.24°C115.15V
726.346A7.048A7.051A2.229A385.05287.836%104530.843.55°C0.989
Row 14 - Cell 0 11.992V4.967V3.277V4.934V438.378Row 14 - Cell 6 Row 14 - Cell 7 Row 14 - Cell 8 53.65°C115.15V
830.211A8.003A8.081A2.439A439.55086.802%121736.243.72°C0.990
Row 16 - Cell 0 11.967V4.950V3.267V4.920V506.382Row 16 - Cell 6 Row 16 - Cell 7 Row 16 - Cell 8 54.85°C115.14V
934.497A8.608A8.589A2.443A494.46085.775%141339.544.58°C0.991
Row 18 - Cell 0 11.942V4.937V3.260V4.912V576.461Row 18 - Cell 6 Row 18 - Cell 7 Row 18 - Cell 8 56.34°C115.14V
1038.603A9.137A9.133A3.069A549.68384.415%166743.945.88°C0.992
Row 20 - Cell 0 11.916V4.925V3.251V4.887V651.170Row 20 - Cell 6 Row 20 - Cell 7 Row 20 - Cell 8 58.08°C115.15V
1143.332A9.150A9.150A3.073A604.87183.177%189646.846.62°C0.993
Row 22 - Cell 0 11.889V4.919V3.245V4.880V727.213Row 22 - Cell 6 Row 22 - Cell 7 Row 22 - Cell 8 59.28°C115.14V
CL10.100A14.001A13.999A0.000A116.08283.017%102729.942.34°C0.973
Row 24 - Cell 0 12.114V4.923V3.282V4.999V139.829Row 24 - Cell 6 Row 24 - Cell 7 Row 24 - Cell 8 50.02°C115.17V
CL245.830A1.000A1.001A1.000A558.73084.924%168044.645.15°C0.992
Row 26 - Cell 0 11.902V5.011V3.281V4.965V657.918Row 26 - Cell 6 Row 26 - Cell 7 Row 26 - Cell 8 58.61°C115.14V

There are no problems under high temperatures and full load conditions. You should not apply such harsh conditions for prolonged periods if you want to keep the PSU alive for long. 

20-80W Load Tests

In the following tests, we measure the PSU's efficiency at loads significantly lower than 10% of its maximum capacity (the lowest load the 80 PLUS standard measures). This is important for representing when a PC is idle with power-saving features turned on.

Swipe to scroll horizontally
Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])PF/AC Volts
11.221A0.494A0.494A0.198A19.98272.501%5466.50.927
Row 2 - Cell 0 12.146V5.071V3.337V5.044V27.561Row 2 - Cell 6 Row 2 - Cell 7 Row 2 - Cell 8 115.15V
22.445A0.987A0.990A0.397A39.97281.829%5678.00.968
Row 4 - Cell 0 12.137V5.064V3.334V5.036V48.848Row 4 - Cell 6 Row 4 - Cell 7 Row 4 - Cell 8 115.15V
33.674A1.482A1.486A0.597A60.00385.157%5888.90.980
Row 6 - Cell 0 12.128V5.058V3.330V5.027V70.462Row 6 - Cell 6 Row 6 - Cell 7 Row 6 - Cell 8 115.15V
44.898A1.980A1.986A0.797A79.95586.854%61010.40.981
Row 8 - Cell 0 12.117V5.051V3.326V5.019V92.057Row 8 - Cell 6 Row 8 - Cell 7 Row 8 - Cell 8 115.15V

The fan spins at low speed with light loads, boosting efficiency by keeping its energy consumption low. 

2% or 10W Load Test

From July 2020, the ATX spec requires 70% and higher efficiency with 115V input. The applied load is only 10W for PSUs with 500W and lower capacities, while for stronger units, we dial 2% of their max-rated capacity.

Swipe to scroll horizontally
Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])PF/AC Volts
10.735A0.232A0.232A0.048A11.12061.692%419<6.00.866
Row 2 - Cell 0 12.144V5.072V3.337V5.048V18.025Row 2 - Cell 6 Row 2 - Cell 7 Row 2 - Cell 8 115.15V

The 60% mark is passed, but the 70% mark is far away. 

Efficiency & Power Factor

Next, we plotted a chart showing the PSU's efficiency at low loads and loads from 10 to 110% of its maximum rated capacity. The higher a PSU’s efficiency, the less energy goes wasted, leading to a reduced carbon footprint and lower electricity bills. The same goes for Power Factor.

Efficiency with normal loads is high, achieving top place compared to other Bronze-rated (in the 80 PLUS scheme) units. On the other hand, with a 2% load, the CX550F doesn't do so well. 

5VSB Efficiency

Swipe to scroll horizontally
Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts
10.100A0.50474.118%0.108
5.046V0.680115.15V
20.250A1.26077.970%0.212
5.042V1.616115.15V
30.550A2.76879.267%0.314
5.034V3.492115.15V
41.000A5.02279.917%0.376
5.022V6.284115.16V
51.500A7.51479.530%0.410
5.010V9.448115.16V
62.999A14.91277.116%0.456
4.972V19.337115.16V

The 5VSB rail has higher efficiency than the average. There is still room for improvement, though. 

Power Consumption In Idle And Standby

Swipe to scroll horizontally
Mode12V5V3.3V5VSBWattsPF/AC Volts
Idle12.150V5.072V3.337V5.051V6.0140.535
Row 2 - Cell 0 Row 2 - Cell 1 Row 2 - Cell 2 Row 2 - Cell 3 Row 2 - Cell 4 Row 2 - Cell 5 115.2V
StandbyRow 3 - Cell 1 Row 3 - Cell 2 Row 3 - Cell 3 Row 3 - Cell 4 0.0550.009
Row 4 - Cell 0 Row 4 - Cell 1 Row 4 - Cell 2 Row 4 - Cell 3 Row 4 - Cell 4 Row 4 - Cell 5 115.2V

Vampire power is low. 

Fan RPM, Delta Temperature, And Output Noise

All results are obtained between an ambient temperature of 37 to 47 degrees Celsius (98.6 to 116.6 degrees Fahrenheit).

(Image credit: Tom's Hardware)

(Image credit: Tom's Hardware)

Under harsh conditions, the fan speed profile is not aggressive since the fan's RPMs increase linearly. 

The following results were obtained at 30 to 32 degrees Celsius (86 to 89.6 degrees Fahrenheit) ambient temperature.       

(Image credit: Tom's Hardware)

(Image credit: Tom's Hardware)

At normal operating temperatures, close to 30 degrees Celsius, the PSU is silent with loads up to 300W. The 30dBA mark is passed with 350W and higher loads, while the PSU enters the 35-40dBA zone with 400W. 

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Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.

  • Panzerbjorne39
    Curious why a rifle bearing fan is listed here under a Pro. Isn’t that the cheaper and louder of the common fan bearings?
    Reply