Corsair AX850 850 W 21

Corsair AX850 850 W Review

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Test Setup

All measurements are performed utilizing a custom designed and built load tester, called Faganas, which is able to stress PSUs up to 1800 Watts. We also use a DS1M12 (Stingray) oscilloscope, a CHY 502 thermometer, a Fluke 175 multimeter and an Instek GPM-8212 power meter. Furthermore, in our setup we have included a wooden box, which along with a heating element is used as a Hot Box. Finally, we have at our disposal three electronic loads (Array 3711A, 300W), a Rigol 1052E oscilloscope and a CEM DT-8852 sound level meter. In the near future we plan to acquire six additional loads to complete our new test set up, which with the help of our custom built software will have the same capabilities with the, ultra expensive, Chroma ATEs. In this article you will find more details about our equipment and the review methodology we follow.

Voltage Regulation Charts

The following charts show the voltage values of the main rails, recorded over a range from 60W to the maximum specified load, and the deviation (in percent), when compared with the voltage values at 60W load.

Efficiency Chart

In this chart you will find the efficiency of AX850 at low loads and at loads equal to 20-100% of PSU’s maximum rated load.

Voltage Regulation and Efficiency Measurements

The first set of tests reveals the stability of voltage rails and the efficiency of AX850. The applied load equals to (approximately) 20%, 40%, 50%, 60%, 80% and 100%, of the maximum load that the PSU can handle. In addition, we conduct two more tests. In the first we stress the two minor rails (5V & 3.3V) with the maximum load that our tester can apply to these rails, while the load at +12V is only 2A and in the second test we dial the maximum load that +12V can handle while load at minor rails is minimum.

Voltage Regulation & Efficiency Testing Data
Corsair AX850
Test12 V5 V3.3 VPower
20% Load13.037A1.904A2.182A175.05W88.43%44.8°C0.860
40% Load24.445A4.797A6.043A339.35W90.97%45.6°C0.912
50% Load29.359A6.757A8.074A413.93W90.83%47.1°C0.933
60% Load37.112A6.748A8.067A506.46W90.95%48.9°C0.943
80% Load50.393A8.861A9.816A679.09W89.95%49.5°C0.958
100% Load64.448A8.845A9.797A843.74W88.72%51.4°C0.963
Crossload 11.972A19.745A17.109A174.26W80.53%49.9°C0.874
Crossload 270.476A1.855A2.117A858.67W89.40%52.3°C0.965

Efficiency is very high and through out 40%-60% load it reached 91%, although the PSU was operating at above 45°C ambient. This is something you don't see everyday. As for voltage regulation now, +12V and 5V managed to stay below 3%, with 2.01% and 2.52% deviation respectively. The 3.3V rail was the lo(o)ser one with 3.95% deviation. If the PSU managed to keep all three rails under 3% we would be very happy but at least the great efficiency compensated us. Finally PF readings were low and actually at test#1 the PSU didn't passed 0.9 PF, the limit that the 80PLUS Gold requires. How ever this is not a problem for a residual consumer that pays only for real (active) power. Finally at room temperature the PSU's fan does not spin at all, since it is programmed to work after a specific temperature, inside the PSU, is reached. However inside our hot box with 45-50°C ambient the fan was, of course, constantly working.

Efficiency at Low Loads

In the next tests, we measure the efficiency of AX850 at loads much lower than 20% of its maximum rated load (the lowest load that the 80 Plus Standard measures). The loads that we dial are (approximately) 40, 65 and 90W. This is important for scenarios in which a typical office PC is in idle with power saving turned on.

Efficiency at Low Loads
Corsair AX850
Test #12 V5 V3.3 VPower

Efficiency with 41W load is nothing to write home about. However the situation dramatically changes with over 66W load and efficiency gets a significant boost as it easily passes the 80% mark.

Power Consumption in Idle & Standby

In the table below you will find the power consumption and the voltage values of all rails (except -12V), when the PSU is in idle mode (On but without any load at its rails) and the power consumption when the PSU is in standby (without any load at 5VSB).

Idle / Standby
Corsair AX850
Mode12 V5 V3.3 V5VSBPower (AC)PF/AC Volts
Standby 0.24W0.015

With only 0.24W phantom power the AX850 is definitely ErP Lot 6 compliant.
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