XPG Core Reactor 850W Power Supply Review

The XPG Core Reactor with 850W max power offers good performance and build quality, but it's expensive for what you get.

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

The load regulation at +12V is not tight enough, while on the minor rails, it is satisfactory.

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 is longer than 20ms and the power-ok signal is accurate. 

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.

The inrush currents are at low enough levels, with both voltage inputs. 

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.

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Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])Temps (In/Out)PF/AC Volts
15.191A1.980A1.994A0.994A84.95786.339%6379.3 40.25°C0.978
12.203V5.052V3.312V5.034V98.399 45.29°C115.14V
211.502A2.972A2.990A1.194A170.02890.579%6409.4 40.41°C0.987
12.096V5.048V3.309V5.027V187.713 46.01°C115.13V
318.117A3.469A3.493A1.395A255.03791.675%6439.4 41.22°C0.990
12.087V5.045V3.307V5.021V278.196 47.00°C115.13V
424.708A3.966A3.993A1.596A340.04891.571%6489.6 41.73°C0.988
12.095V5.043V3.306V5.015V371.349 48.14°C115.12V
530.800A4.960A4.995A1.797A424.96591.082%97520.5 42.65°C0.989
12.158V5.039V3.304V5.009V466.574 49.70°C115.12V
636.990A5.960A5.999A2.000A509.51190.168%147232.2 42.79°C0.991
12.157V5.036V3.301V5.003V565.070 50.45°C115.11V
743.268A6.958A7.006A2.202A594.87089.500%179739.0 42.97°C0.992
12.151V5.032V3.298V4.996V664.656 51.03°C115.11V
849.542A7.959A8.009A2.406A680.20688.747%207342.6 43.60°C0.993
12.147V5.028V3.296V4.989V766.457 52.74°C115.13V
956.215A8.460A8.500A2.407A765.13388.069%226644.7 44.77°C0.994
12.143V5.025V3.294V4.987V868.787 54.78°C115.15V
1062.636A8.963A9.023A3.019A849.98887.280%229045.7 44.79°C0.995
12.138V5.021V3.292V4.970V973.864 55.67°C115.13V
1169.619A8.967A9.025A3.020A934.75486.524%228645.6 46.54°C0.995
12.138V5.020V3.291V4.968V1080.336 57.86°C115.14V
CL10.117A14.002A14.000A0.000A118.18884.109%663 10.2 42.76°C0.985
12.118V5.040V3.300V5.069V140.517 49.51°C115.16V
CL270.846A0.999A1.001A1.000A872.99287.771%2170 43.6 44.93°C0.995
12.134V5.033V3.301V5.015V994.627 55.47°C115.14V

The +12V rail's voltage goes up and down instead of a linear decrease as the load increases. This has to do mostly with the resonant controller. 

The fan profile with higher than typical loads should be looser, even if CWT had to make some changes on the platform and use proper heat sinks on the secondary side. 

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.

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Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])PF/AC Volts

The efficiency at light loads is excellent! 

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.

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Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan Speed (RPM)PSU Noise (dB[A])PF/AC Volts

Thanks to the new Champion resonant controller and its burst mode operation, the efficiency at super light loads easily exceeds 70%. 


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.

This is a highly efficient power supply, especially under light and super-light loads. 

5VSB Efficiency

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Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts

The 5VSB rail is also highly efficient. 

Power Consumption In Idle And Standby

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Mode12V5V3.3V5VSBWattsPF/AC Volts

The vampire power levels are restricted with both voltage inputs. 

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)

The fan profile should be more relaxed, under higher loads at increased operating temperatures. The overall output noise output of our sample is notably higher compared to the Cybenetics results, and this is an indication that the standard production batches use a different fan speed profile (Cybenetics usually tests pre-production samples).

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)

Up to typical loads (around 420W), the fan spins at its lowest speed, where it is inaudible. With about 130W more, though, it exceeds 30 dB(A), and with more than 740W, the noise goes over 40 dB(A).

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Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a contributing editor at Tom's Hardware, covering PSUs.

  • Olle P
    Hardware-wise this seems like a great PSU.
    One good thing that wasn't listed is that the housing actually adhere to the ATX-format! (Most PSUs have the wrong length.)
  • Darkbreeze
    There are no standards for depth on ATX power supplies. They vary from model to model and it has been that way since forever. Even within the same brand. This is nothing new. There is no ATX format regarding depth for it to adhere TO.

    Aris. Any idea yet whether all three capacities of this power supply are using the same platform and have the same expected or similar performance and characteristics or no idea at this time? Thanks.
  • Yeca
    I got one of this recently for a new build, and being the paranoic person that i am, i bought a psu tester and it showed a 80ms PG result. The 12V, 5V and 3.3V results were alright. Is this something i should worry about?
  • Darkbreeze
    You should start your own thread. This is not the place for such questions.
  • Yeca
    Darkbreeze said:
    You should start your own thread. This is not the place for such questions.
    Got it, thanks!