Corsair AX760i 760 W Review 29

Corsair AX760i 760 W Review

Efficiency & Temperatures »

Test Setup

All measurements were performed using two Chroma 6314A mainframes equipped with the following electronic loads: six 63123A [350 W each], one 63102A [100 W x2], and one 63101A [200 W]. The aforementioned equipment is capable of delivering 2500 W of load, and all loads are controlled by a custom-made software. We also used a Picoscope 3424 oscilloscope, a Picotech TC-08 thermocouple data logger, a Fluke 175 multimeter, and a Yokogawa WT210 power meter. We also included a wooden box, which, along with some heating elements, was used as a hot box. Finally, we had at our disposal four more oscilloscopes (Rigol 1052E and VS5042, Stingray DS1M12, a second Picoscope 3424), and a CEM DT-8852 sound-level meter. In this article, you will find more details about our equipment and the review methodology we follow. Finally, we conduct all of our tests at 40 - 45°C ambient in order to simulate with higher accuracy the environment seen inside a typical system, with 40 - 45°C being derived from a standard ambient assumption of 23°C and 17 - 22°C being added for the typical temperature rise within a system.

Primary Rails Voltage Regulation

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) for the same load range.







5VSB Regulation

The following chart shows how the 5VSB rail deals with the load we throw at it.


Hold-up Time

The hold-up time is a very important characteristic of a PSU and represents the amount of time, usually measured in milliseconds, that a PSU can maintain output regulations as defined by the ATX spec without input power. In other words, it is the amount of time that the system can continue to run without shutting down or rebooting during a power interruption. The ATX spec sets the minimum hold-up time to 16 ms at maximum continuous output load. In the following screenshot, the blue line is the mains signal and the yellow line is the "Power Good" signal. The latter is de-asserted to a low state when any of the +12V, 5V, or 3.3V output voltages fall below the undervoltage threshold, or after the mains power has been removed for a sufficiently long time to guarantee that the PSU cannot operate anymore.



For the first time we have a unit that features a higher hold-up time than the ATX threshold. This means that appropriate capacitors with enough capacity to provide energy to the secondary side once a power interruption occurs were used in the APFC section. Well done Corsair!

Inrush Current

Inrush current or switch-on surge refers to the maximum, instantaneous input-current drawn by an electrical device when first turned on. Because of the charging current of the APFC capacitor(s), PSUs produce large inrush-current right as they are turned on. Large inrush current can cause the tripping of circuit breakers and fuses and may also damage switches or relays; as a result, the lower the inrush current of a PSU right as they are turned on, the better.



The inrush current is relatively low for a unit of this capacity. This is, of course, very good news.

Voltage Regulation and Efficiency Measurements

The first set of tests revealed the stability of the voltage rails and the efficiency of the AX760i. The applied load was equal to (approximately) 20%, 40%, 50%, 60%, 80%, 100% and 110% of the maximum load that the PSU can handle. In addition, we conducted two more tests. In the first test, we stressed the two minor rails (5V and 3.3V) with a high load while the load at +12V was only 2 A, and, in the second test, we dialed the maximum load that the +12V rail could handle while the load on the minor rails was minimal.

Voltage Regulation & Efficiency Testing Data
Corsair AX760i
Test12 V5 V3.3 V5VSBPower
(DC/AC)
EfficiencyFan SpeedTemp
(In/Out)
PF/AC
Volts
20% Load10.805A1.992A1.997A1.001A151.76W
(172.3W)
90.77%
(99%)
0 RPM 48.07°C
(50.5°C)
0.978
12.046V5.023V3.301V4.996V167.20W
(174W)
44.92°C230.1V
40% Load21.968A3.988A4.004A1.200A303.69W
(327W)
93.64%
(98.5°C)
476 RPM 43.06°C
(44.8°C)
0.994
12.042V5.011V3.294V4.984V324.33W
(332W)
50.05°C230.0V
50% Load27.428A4.975A5.012A1.605A379.57W
(407.9W)
93.76%
(99%)
624 RPM 43.46°C
(43.8°C)
0.996
12.037V5.013V3.290V4.978V404.85W
(412W)
51.02°C229.9V
60% Load32.889A5.984A6.004A2.010A455.56W
(459W)
93.69%
(93.1%)
760 RPM 43.57°C
(43.5°C)
0.997
12.035V5.008V3.296V4.965V486.23W
(493W)
51.78°C229.9V
80% Load43.989A7.989A8.019A2.419A607.47W
(616W)
93.23%
(93.9%)
1044 RPM 44.22°C
(44.8°C)
0.999
12.029V5.002V3.291V4.951V651.60W
(656W)
52.81°C229.9V
100% Load55.703A9.025A9.048A3.045A759.33W
(779W)
92.48%
(94.7%)
1532 RPM 46.04°C
(45.3°C)
0.999
12.022V4.985V3.282V4.922V821.05W
(823W)
54.88°C229.8V
110% Load62.036A9.028A9.043A3.045A835.23W
(864W)
92.09%
(95%)
1756 RPM 47.35°C
(46.8°C)
0.999
12.018V4.984V3.284V4.922V906.95W
(909W)
57.02°C229.7V
Crossload 11.965A15.003A15.005A0.502A150.91W
(180.2W)
86.83%
(99%)
1064 RPM 45.98°C
(47.5°C)
0.980
12.043V5.002V3.311V5.015V173.81W
(182W)
52.22°C230.2V
Crossload 263.287A1.000A1.003A1.002A774.07W
(792W)
92.90%
(94.7%)
1560 RPM 46.21°C
(45.8°C)
0.999
12.021V5.002V3.292V4.981V833.20W
(836W)
54.37°C229.8V

The unit had, first of all, no problem at all delivering even more than its full power at ambient temperatures that exceeded 45°C. This simply means that all components can easily handle the max power of the PSU while taking much abuse at high operating temperatures.

Efficiency is sky high and is currently the highest we have ever measured with our new and highly accurate set-up. Efficiency is, with a typical load, almost 94%; an impressive reading. This advantage is clearly due to the digital-control component as opposed to other conventional methods. Voltage regulation is also outstanding on all rails, and fan RPM is, up to 60% load, kept low as well, which results in equally low output noise. Only after highly stressing the unit did the fan operate at high speed, which resulted in audible noise output. Finally, the PSU's PF readings are out of this world. We have, with the exception of the AX1200i, never seen a PSU register such a high PF.

As for the Corsair Link software, its efficiency readings are, most of the times, way off, although the measured DC power is, from 40% load and upwards, close enough to the actual and real DC power reading. Voltage readings are steady throughout all load ranges since the PSU has amazing voltage regulation. AC voltage readings are, of course, only off by a little bit (by 1.5 - 2 V). Unfortunately, no similar implementations we tried in the past (AX1200i, EVGA SuperNOVA NEX1500, and Thortech PSUs) managed to provide accurate enough readings, which meant that our expectations weren't high.

Several screenshots of the Corsair Link software, which we took during out test sessions, follow. The order of the screenshots is the same as the order of the tests shown in the table above (20% load test to Cross-load 2).

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