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 Voltage 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.



The two Chemi-Con bulk caps easily allowed the unit to pass the minimum allowed hold-up time the ATX spec sets.

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.



Because of the large thermistor, registered inrush current was pretty low for a 1.5 kW unit.

Voltage Regulation and Efficiency Measurements

The first set of tests revealed the stability of the voltage rails and the efficiency of the AX1500i. The applied load was equal to (approximately) 10%-110% of the maximum load the PSU can handle, in 10% increments.

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 was minimal.

What to comment on first? The absolutely mind-blowing voltage regulation? The insanely high efficiency with every load we dialed in, or the fact that the unit easily delivered 1.65 kW at almost 49°C ambient? There is no doubt that this PSU is better than the already great AX1200i, and it manages to register efficiency well above Platinum levels despite its higher capacity, which makes things much harder at high loads. We won't compare our efficiency results to the insane 80 Plus Titanium 230V EU specification which, for the record, requires 90% at 10% load, 94% at 20%, 96% at 50% and 94% at full load, because we conduct our tests at much higher ambient temperatures than 80 PLUS and the unit is only Titanium certified with 115 VAC input.

What matters here is that the it is the most efficient PSU we have tested to date, and it also scored the best voltage regulation we have ever seen, on nearly all rails. The only exception was 5VSB, which doesn't matter. A technological miracle, Corsair and Flextronics managed to give us a glimpse of what to expect from PSUs still to come. Such performance also gives the competition a good reason to explore DSP with their own products.

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 shown in the table above (10% load to Cross-load 2).