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Corsair HX850 PSU Review

Load Regulation, Hold-Up Time & Inrush Current

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

Primary Rails And 5VSB Load Regulation

Load Regulation testing is detailed here.

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Hold-Up Time

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

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The hold-up time we observe is long, as is the power-good signal's delay (it's among the longest we have measured so far).

Inrush Current

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

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Our inrush current measurements are normal with 115V input. However, they're high with 230V input.

Load Regulation And Efficiency Measurements

The first set of tests reveals the stability of the voltage rails and the HX850'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 compatible with Intel's C6/C7 sleep states 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 SpeedPSU NoiseTemps (In/Out)PF/AC Volts
15.245A1.986A1.984A0.996A84.84087.275%0 RPM<6.0 dB(A)46.57°C0.973
211.525A2.974A2.979A1.196A169.67591.245%0 RPM<6.0 dB(A)46.86°C0.992
318.189A3.478A3.494A1.396A254.90792.286%0 RPM<6.0 dB(A)47.48°C0.995
424.849A3.975A3.979A1.595A339.76592.430%0 RPM<6.0 dB(A)48.15°C0.997
531.179A4.974A4.976A1.801A424.69092.130%0 RPM<6.0 dB(A)48.96°C0.998
637.525A5.975A5.977A2.002A509.66391.579%730 RPM19.5 dB(A)41.34°C0.998
743.887A6.981A6.978A2.205A594.68690.942%730 RPM19.5 dB(A)41.72°C0.999
850.272A7.986A7.980A2.406A679.61190.286%855 RPM22.4 dB(A)42.77°C0.999
957.098A8.483A8.501A2.409A764.60689.606%1030 RPM27.2 dB(A)43.93°C0.999
1063.679A8.997A8.991A3.019A849.47088.903%1100 RPM29.3 dB(A)44.73°C0.999
1170.884A9.003A8.998A3.021A934.37188.073%1280 RPM33.4 dB(A)46.19°C0.999
CL10.100A18.027A18.002A0.005A151.70783.968%855 RPM22.4 dB(A)44.30°C0.992
CL270.796A1.003A1.001A1.002A858.22189.281%1140 RPM30.5 dB(A)44.87°C0.999

At 1.15%, load regulation is fairly good on the +12V rail. It's within 1% on the minor rails, while the 5VSB rail features super-tight load regulation compared to what we're used to.

When it comes to efficiency, the HX850 has no problem with 80 PLUS' Platinum requirements at 20% and 50% of its max-rated-capacity load. Under full load, it comes very close. Under normal operating temperatures (80 PLUS only tests at 23°C +/-5°C), we are pretty sure that the HX850 would easily pass the full load efficiency requirement as well.

The PSU's noise stays very low during our worst-case overload (110%) scenario, where it generates less than 34 dB(A). Corsair does a marvelous job in this discipline, making its HX850 one of the quietest 850W units we've reviewed.

Finally, the APFC converter is well-designed. Its readings are sky-high, even during the 10% load test.

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