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 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 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 is significantly lower than the minimum allowed one. It is thankfully still higher than 10 ms.

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



The measured inrush current is normal for a unit with a capacity of 1 kW, but there are other PSUs of a similar capacity that register way lower inrush currents because of their sophisticated design (see at the NZXT HALE 90 V2 1000 W entry of the above graph).

Voltage Regulation and Efficiency Measurements

The first set of tests revealed the stability of the voltage rails and the efficiency of the Tesla R2 1000 W. The applied load was equal to (approximately) 20%, 40%, 50%, 60%, 80%, 100%, and 110% of the maximum load that the PSU can handle. 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 2 A. In the second test, we dialed the maximum load that the +12V rail could handle while the load on the minor rails was minimal.


Overall voltage regulation was very good, with the 5V rail scoring the smallest deviation of all rails. Efficiency is pretty high throughout the entire load range, despite the high ambient temperatures at which we conducted our tests. Also, the fan was quiet enough during the first tests but ramped up when things got tough, making it annoyingly loud once high loads were combined with high operating temperatures; but this is a scenario that a user will hardly encounter since it is very difficult to actually stress a 1 kW unit while keeping ambient inside the case high. Another pleasant surprise were the very high PF readings that we got on all tests. Even with a 20 % load, PF was close to 0.95, which we don't see very often. Sure, residential consumers only pay for the real power they consume, but it is still nice to see desktop PSUs with such high PF readings since a high PF curtails the energy that is wasted, which helps in keeping a safer and cleaner environment.