Riotoro Enigma 850W PSU Review

Load Regulation, Hold-Up Time, And Inrush Current

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

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Primary Rails And 5VSB Load Regulation

Load Regulation testing is detailed here.

Hold-Up Time

Our hold-up time tests are described in detail here.

The registered hold-up time we measured is low. The only good news is that Great Wall tuned the power-good signal to drop before the rails go out of spec. Still, we'd like to see the delay closer to 1ms, as the ATX spec requires.

Inrush Current

For details on our inrush current testing, please click here.

The inrush current is low with 115V input, and at normal levels with 230V.

Load Regulation And Efficiency Measurements

The first set of tests reveals the stability of the voltage rails and the Enigma 850's efficiency. The applied load equals (approximately) 10 to 110 percent of the PSU's maximum load in increments of 10 percentage points.

We conducted two additional tests. During the first, we stressed the two minor rails (5V and 3.3V) with a high load, while the load at +12V was only 0.1A. This test reveals whether a PSU is Haswell-ready or not. In the second test, we determined the maximum load the +12V rail could handle with minimal load on the minor rails.

Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed
Fan Noise
Temps (In/Out)PF/AC Volts
15.221A1.965A1.975A0.996A84.75386.136%825 RPM
25.9 dB(A)
38.56°C0.955
12.102V5.083V3.338V5.007V98.39441.50°C115.07V
211.482A2.950A2.971A1.198A169.60490.210%870 RPM27.0 dB(A)39.39°C0.960
12.086V5.070V3.330V4.993V188.01142.54°C115.06V
318.125A3.456A3.489A1.405A254.86291.060%905 RPM29.4 dB(A)39.47°C0.972
12.071V5.061V3.322V4.978V279.88343.44°C115.06V
424.759A3.954A3.979A1.611A339.68990.994%1020 RPM31.8 dB(A)39.88°C0.979
12.057V5.053V3.315V4.965V373.30945.04°C115.05V
531.067A4.967A4.988A1.815A424.68090.553%1140 RPM35.3 dB(A)41.70°C0.984
12.044V5.040V3.307V4.948V468.98447.29°C115.05V
637.388A5.967A6.001A2.025A509.58689.827%1210 RPM37.6 dB(A)41.91°C0.987
12.031V5.026V3.298V4.933V567.29448.64°C115.05V
743.724A6.987A7.020A2.235A594.56888.966%1295 RPM39.8 dB(A)42.78°C0.990
12.018V5.013V3.288V4.915V668.30650.55°C115.06V
850.076A8.003A8.049A2.446A679.45987.983%1430 RPM41.9 dB(A)44.19°C0.992
12.003V5.000V3.280V4.898V772.25852.87°C115.10V
956.884A8.516A8.584A2.451A764.50487.075%1575 RPM43.7 dB(A)44.59°C0.993
11.988V4.990V3.273V4.891V877.98254.54°C115.06V
1063.437A9.045A9.093A3.084A849.30185.903%1680 RPM45.2 dB(A)45.65°C0.994
11.974V4.979V3.265V4.858V988.67757.03°C115.06V
1170.620A9.056A9.106A3.089A934.19284.809%1680 RPM45.2 dB(A)46.44°C0.995
11.958V4.974V3.260V4.852V1101.53058.54°C115.05V
CL10.100A16.027A16.004A0.004A133.64483.910%1095 RPM33.5 dB(A)42.81°C0.960
12.098V4.980V3.287V5.019V159.27148.68°C115.10V
CL270.791A1.003A1.003A1.002A860.74486.253%1680 RPM45.2 dB(A)46.51°C0.994
11.971V5.041V3.297V4.956V997.92957.31°C115.06V

Load regulation at +12V is tight enough. On the minor rails it falls within 2.5%, so we consider that satisfactory. The 5VSB rail in these tests suffers a greater deviation of around 3.7%, but because it's still within the ATX specification, we aren't concerned.

The Enigma's fan profile is quite relaxed up to the 40% load test, and output noise exceeds 40 dB(A) only at higher loads with 80% of the PSU's maximum-rated capacity. Although the max temperature for full power delivery is restricted at 40°C, Great Wall still tuned the fan profile for higher operational temperatures. This is a good thing, of course.

Our results show the Enigma easily meeting the 80 PLUS Gold requirements with 20% and 50% load. However, it falls short during the full-load test where it should achieve at least 87% efficiency. As we already know, though, 80 PLUS conducts its tests at low ambient temperatures, where efficiency is higher.

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  • WhyAreYou
    Great review!