SilverStone SX750 Platinum SFX Power Supply Review

To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units. 

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 and, at the same time, it applies less stress to the DC-DC converters that many system components utilize.

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Results 1-8: Load Regulation

Load regulation is satisfactory at 12V, but we cannot state the same for the minor rails. 

Hold-Up Time

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

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Results 9-12: Hold-Up Time

The hold-up time is extremely short. The power ok signal is accurate, at least. 

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.

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Results 13-14: Inrush Current

The inrush current is on the high side, with 230V input. 

Leakage Current

In layman's terms, leakage current is the unwanted transfer of energy 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 the majority of cases is connected to the ground. For measuring leakage current, we use a GW Instek GPT-9904 electrical safety tester instrument.

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 and it is defined by the IEC-60950-1 regulation, ensuring that the current is low and will not harm any person coming in contact with the power supply's chassis.

Leakage current is low and at the same level with the SX1000 Platinum. 

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.

PF readings are extremely high with 115V input. However, we don't frequently see perfect PF scores (1.000). Moreover, the PSU can handle increased operating temperatures, but the output noise is high since the 92mm fan has to spin at high speeds to cope with the thermal load. 

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.

The fan doesn't spin at light loads, even with temperatures exceeding 35 degrees Celsius. The efficiency levels are not high, though, in the first two tests. 

2% or 10W Load Test

Intel plans on raising the ante at efficiency levels under ultra-light loads. So from July 2020, the ATX spec will require 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.

The PSU scores bottom low efficiency, with 2% of its max-rated capacity load. Obviously, burst mode is not utilized to achieve high efficiency at super light loads. 

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.

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Results 15-18: Efficiency

The efficiency levels are not high, especially with 2% load. Enhance needs to make some modifications to this platform for higher efficiency. 

5VSB Efficiency

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Results 19-20: 5VSB Efficiency

The 5VSB rail is highly efficient!

Power Consumption In Idle And Standby

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Results 21-22: Vampire Power

Vampire power is a bit on the high side, but still way below the 0.25W limit. 

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).

The fan speed profile is aggressive, under high operating temperatures, and in combination with the DBB fan this is not the ideal scenario. 

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

The fan's passive operation doesn't last long, even under normal operating temperatures, and the PSU quickly enters the 30-35 dBA zone, which can be annoying for users sensitive to noise. However, with higher than 400W loads, the PSU starts to make its presence well felt. 

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