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, VS5042, Stingray DS1M12, and another 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 of only 1 ms fails to comply with ATX spec requirements, which is a shame. The platform does, in our opinion, require several design upgrades, since the APFC cap is large enough for the capacity of the unit.

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.



Inrush current is among the highest we have ever measured, and this is only a medium-capacity PSU. Apparently, a larger thermistor is needed to lower the inrush current. The measured reading is thankfully still below 50 A.

Voltage Regulation and Efficiency Measurements

The first set of tests revealed the stability of the voltage rails and the efficiency of the ST65F-G. 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.


The PSU easily managed to deliver more than its full power at 46°C, proving that Enhance should raise the maximum operating temperature threshold of their new PSUs. The OTP circuit didn't engage during our entire test session; however, the fan control circuit forced the fan to operate at its full speed most of the time. The Delta difference between the input and the output of the PSU was, nonetheless, relatively small—the fan doesn't provide enough airflow, or the large heatsinks block the airflow along with other components.

Efficiency at 20% load was kind of low for a Gold unit, but increased to the levels we expected during the other tests. With a 50% of maximum-rated-capacity load, it peaked with a marginal reading over 91%. Overall, this is definitely not the most efficient Gold unit we have ever tested, but it is still efficient enough. As for voltage regulation, Silverstone's claim of 3% on all rails proved to be true, and the +12V and 5V rails even have tighter voltage regulation. Also, during the CL1 test, the voltage readings of the minor rails proved that the small VRMs generating them pack more power than meets the eye, since they easily delivered 150 W together.