SilverStone SX700-G PSU Review: An Overclocked SX650-G?

Load Regulation, Hold-Up Time, Inrush Current, Efficiency & Noise

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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 improves system stability, especially under overclocked conditions. At the same time, it applies less stress to the DC-DC converters that many system components utilize.

SilverStone's load regulation isn't particularly tight on every rail. The Corsair SF family clearly dominates in this discipline.

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.

The hold-up time we measured is closer to 17ms than we expected, while the power-good signal is accurate. It would be nice if SilverStone used a larger bulk cap, rather than the same one we found in the SX650-G. Nevertheless, the SX700-G takes the lead from its principal competition, Corsair's SF750, in these tests.

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.

Measured inrush currents are at normal levels.

10-110% Load Tests

These tests reveal the SX700-G’s load regulation and efficiency levels under high ambient temperatures. They also show how the fan speed profile behaves under tough operating conditions.

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed
PSU Noise
Temps (In/Out)PF/AC Volts
13.947A1.971A1.962A0.989A69.45482.827%1285 RPM
16.8 dB(A)
40.21°C0.976
12.131V5.069V3.355V5.054V83.85444.34°C115.07V
28.966A2.964A2.957A1.190A139.52288.030%1290 RPM16.8 dB(A)41.71°C0.991
12.116V5.059V3.347V5.041V158.49446.59°C115.06V
314.331A3.464A3.439A1.393A209.50890.380%1298 RPM17.0 dB(A)42.15°C0.992
12.108V5.051V3.341V5.027V231.80747.45°C115.10V
419.711A3.966A3.955A1.596A279.51590.871%1296 RPM16.9 dB(A)42.51°C0.994
12.091V5.043V3.334V5.014V307.59447.96°C115.49V
524.775A4.967A4.958A1.800A349.65090.816%1296 RPM16.9 dB(A)42.46°C0.995
12.075V5.033V3.326V5.001V385.00949.26°C115.15V
629.853A5.972A5.968A2.006A419.76490.379%1626 RPM24.1 dB(A)42.63°C0.996
12.058V5.023V3.317V4.987V464.44849.61°C115.15V
734.947A6.983A6.979A2.213A489.89189.748%2096 RPM33.2 dB(A)43.08°C0.997
12.041V5.012V3.309V4.972V545.85250.90°C115.07V
840.060A7.998A7.999A2.421A560.03688.992%2609 RPM39.4 dB(A)43.98°C0.997
12.023V5.001V3.300V4.957V629.31152.35°C115.07V
945.581A8.512A8.502A2.424A629.74288.367%2860 RPM42.2 dB(A)44.50°C0.997
12.006V4.993V3.293V4.950V712.64353.72°C115.10V
1051.116A9.031A9.036A2.531A700.08787.629%2857 RPM42.2 dB(A)45.55°C0.997
11.990V4.984V3.286V4.940V798.92555.41°C115.10V
1157.009A9.046A9.052A2.535A769.72986.775%2854 RPM42.2 dB(A)46.66°C0.997
11.972V4.977V3.280V4.933V887.03757.27°C115.07V
CL10.132A13.000A12.999A0.000A109.95382.341%1320 RPM17.4 dB(A)42.28°C0.992
12.128V5.019V3.316V5.066V133.53349.87°C115.09V
CL258.340A1.001A0.998A1.000A712.77288.087%2870 RPM42.4 dB(A)45.43°C0.997
11.989V5.017V3.315V5.002V809.16755.54°C115.08V

Up through the 60% load test, SilverStone's fan noise is low. However, it notably increases in the following two tests. At 90% of its maximum-rated capacity and higher, the fan rotates at its peak speed, generating a raucous 42+ dB(A).

20-80W Load Tests

In the following tests, we measure the SX700-G's efficiency at loads significantly lower than 10 percent 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.

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed
PSU Noise
PF/AC Volts
11.169A0.490A0.473A0.197A19.27861.101%1273 RPM
16.8 dB(A)
0.908
12.145V5.079V3.363V5.086V31.551115.07V
22.428A0.983A0.979A0.394A39.75665.592%1279 RPM16.8 dB(A)0.969
12.141V5.075V3.360V5.075V60.611115.06V
33.612A1.476A1.456A0.592A59.19882.150%1282 RPM16.8 dB(A)0.979
12.133V5.072V3.357V5.069V72.061115.06V
44.870A1.972A1.962A0.791A79.64584.113%1283 RPM16.8 dB(A)0.979
12.129V5.068V3.354V5.059V94.688115.07V

Measured noise is low. But the same applies to the efficiency levels we recorded, too. In the first two tests, they're lower than 70%.

Efficiency

Next, we plotted a chart showing the SX700-G’s efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity. The higher a PSU’s efficiency, the less energy gets wasted as heat.

Efficiency is high enough under normal loads. However, that's not the case under light loads where the SX700-G lands in last place.

5VSB Efficiency

Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts
10.100A0.51070.932%0.114
5.095V0.719115.09V
20.250A1.27275.490%0.217
5.089V1.685115.09V
30.550A2.79480.241%0.310
5.079V3.482115.09V
41.000A5.06781.871%0.368
5.066V6.189115.09V
51.500A7.57681.938%0.400
5.050V9.246115.09V
62.500A12.55181.126%0.434
5.020V15.471115.09V

The 5VSB rail achieves high efficiency levels.

Power Consumption In Idle And Standby

Mode12V5V3.3V5VSBWattsPF/AC Volts
Idle12.142V5.082V3.364V5.096V5.8880.502
115.1V
Standby0.0920.016
115.1V

We measure high vampire power levels, at least compared to the competition. This is the reason why SilverStone's 5VSB rail isn't particularly efficient under very light loads.

Fan RPM, Delta Temperature, And Output Noise

All of our results are obtained between 37°C (98.6°F) to 47°C (116.6°F) ambient temperature.   

The following results are obtained between 30°C (86°F) to 32°C (89.6°F) ambient temperature.   

In a range between 1,200 and 1,400 RPM, the fan's minimum speed is quite high. With that said, it's very hard to achieve lower rotational speeds without PWM control.

Up through 350W of load the SX700-G is quiet, generating less than 25 dB(A). But with merely 50W more, it jumps up above 35 dB(A). We think that the fan speed profile should ramp up more smoothly as load increases.

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