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 can 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.



The hold-up time was way lower than the allowed minimum, so the unit registered a major fail in this test.

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.



Compared to other units of similar capacity, inrush current was low.

Load Regulation and Efficiency Measurements

The first set of tests revealed the stability of the voltage rails and the PSU'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 was minimal.

+12V load regulation was pretty tight, but we cannot say the same of the other rails, where we expected such a modern platform to fare better. Modern systems might not use the 5V and 3.3V rails as much, and the 5VSB's regulation is of no concern given it is in spec, but you have to make sure every rail, not just +12V, keeps up with the rather strong competition where every rail does perform as well. Yet the PSU easily delivered more than its full power at very high operating temperatures, proving that it can handle such tough conditions, and output noise was kept at very low levels throughout most of our tests. This is actually one of the quietest high-capacity units available on the market today, which will surely please users in need of 1 kW for a silent system; two aspects PSU OEMs simply couldn't combine successfully only a little while ago. We left the efficiency performance results for last. There were no surprises here since the PSU performed as expected, delivering good efficiency levels in all of our tests. Efficiency peaked at a little over 93% with 40% of the maximum-rated-capacity load and was very close to 90% with the full load.

DPSApp Screenshots

Screenshots of the DPSApp software, which we took during our test sessions, follow. The order of screenshots is the same as the order of the tests shown in the table above (10% load test to Cross-load 2). Voltage readings weren't terribly accurate since they never steered far from their nominal values; however, we were surprised to find efficiency readings to be spot on.

10% Load Test

20% Load Test

30% Load Test

40% Load Test

50% Load Test

60% Load Test

70% Load Test

80% Load Test

90% Load Test

100% Load Test

110% Load Test

CL1 Load Test

CL2 Load Test