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 able to deliver 2500 W of load, and all loads are controlled by a custom-made software. We also used a Rigol DS2072A oscilloscope kindly sponsored by Batronix, a Picoscope 3424 oscilloscope, a Picotech TC-08 thermocouple data logger, two Fluke multimeters (models 289 and 175), 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 three more oscilloscopes (Rigol VS5042, Stingray DS1M12, and a second Picoscope 3424), and a Class 1 Bruel & kjaer 2250-L G4 Sound Analyzer which is equipped with a type 4189 microphone that features a 16.6 - 140 dBA-weighted dynamic range. You will find more details about our equipment and the review methodology we follow in this article. We also conduct all of our tests at 40°C-45°C ambient to simulate the environment seen inside a typical system with a higher accuracy, with 40°C-45°C being derived from a standard ambient assumption of 23°C and 17°C-22°C being added for the typical temperature rise within a system.

Primary Rails Load Regulation

The following charts show the voltage values of the main rails, recorded over a range from 60 W 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

Hold-up time is a very important PSU characteristic and represents the amount of time, usually measured in milliseconds, a PSU can maintain output regulations as defined by the ATX spec without input power. In other words, it is the amount of time the system can continue to run without shutting down or rebooting during a power interruption. The ATX specification sets the minimum hold-up time to 16 ms with the 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.



These bulk caps are larger than in the RM1000, which allowed for a hold-up time over the 16 ms threshold.

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. 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, relays, and bridge rectifiers; as a result, the lower the inrush current of a PSU right as it is turned on, the better.



The good design kept inrush current low.

Load Regulation and Efficiency Measurements

The first set of tests revealed the stability of the voltage rails and the HX1000i's efficiency. The applied load was equal to (approximately) 10%-110% of the maximum load the PSU can handle, in 10% steps.

We conducted two additional 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 0.10 A. This test reveals whether the PSU is Haswell ready or not. In the second test, we dialed the maximum load the +12V rail can handle while the load on the minor rails is minimal.

We would like to see a tighter load regulation on the +12V rail; however, all other rails performed rather well. Especially the 5VSB rail achieved one of the lowest load regulations we have ever measured. Yet its load regulation isn't as important unless it is out of spec. We suspect that the most probable cause for the relatively low load regulation on +12V is Corsair's and CTW's priority on fine-tuning the unit's Platinum-efficiency, and as you can see in the table above, the unit achieved close to 94% efficiency during the 40% load test, an amazing figure for even a Platinum-certified PSU. The HX1000i also didn't have a problem delivering its full power at close to 46°C ambient, while the RM1000 we tested recently had problems doing because its OTP kept triggering.

Output noise was very low overall, making this the quietest 1 kW PSU we have tested so far. The title of quietest PSU belonged to the RM1000 only two reviews ago, but the HX1000i has raised the bar by another notch. Corsair did a nice job sure to please all noise-haters, and the FDB fan obviously played its key role in doing so.

Before we skip to the next page, we would like to draw your attention to the especially accurate power in/out and efficiency readings the Corsair Link software provided. We couldn't ask a $5-$10 digital circuit to provide readings as accurate as a $8,000-$10,000 power meter, but were left astonished with the results after taking measurements which deviated by so very little with the Corsair Link software.

Corsair Link Screenshots

Several screenshots of the Corsair Link software, which we took during our test sessions, follow. The order of these screenshots is the same as the order of the tests in the table above (10% load to Cross-load 2 test).