Test Setup

All measurements are performed utilizing ten electronic loads (seven Array 3711A, 300W each, and three Array 3710A, 150W each), which are able to deliver over 2500W of load and are controlled by a custom made software. We also use a Picoscope 3424 oscilloscope, a CHY 502 thermometer, a Fluke 175 multimeter and an Instek GPM-8212 power meter. Furthermore, in our setup we have included a wooden box, which along with a heating element is used as a Hot Box. Finally, we have at our disposal four more oscilloscopes (Rigol 1052E and VS5042, Stingray DS1M12 and 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, if the manufacturer states that the maximum operating temperature of the test unit is only 40°C then we try to stay near this temperature, otherwise we crank up the heat inside the hotbox up to 50°C.

Voltage Regulation Charts

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 Chart

The following chart shows how the 5VSB rail deals with the load we throw at it.

Efficiency Chart

In this chart you will find the efficiency of VP350P at low loads and at loads equal to 20-100% of PSU’s maximum rated load.

Voltage Regulation and Efficiency Measurements

The first set of tests reveals the stability of voltage rails and the efficiency of VP350P. The applied load equals to (approximately) 20%, 40%, 50%, 60%, 80% and 100%, of the maximum load that the PSU can handle. In addition, we conduct two more tests. In the first we stress the two minor rails (5V & 3.3V) with a high load, while the load at +12V is only 2A and in the second test we dial the maximum load that +12V can handle while load at minor rails is minimal.

Let's start with the good news first. Voltage regulation on the +12V rail is excellent since it is well below 1% and the minor rails feature good voltage regulation too, since they kept their voltages within 3% range. Obviously the small capacity of the PSU played a key role in this. Overall the small Antec performed admirably well regarding voltage regulation with balanced loads. Also it had no trouble at all delivering full power with high operating temperatures, something that probably would have heavily damaged other, similar priced, PSUs. Finally the unit's fan didn't produce much noise even at full load.
Now it's time for the bad news. First, efficiency is low for today's standards and with 20% load it is below the 80% mark. Also the group regulation design, used in the secondary side of the PSU, heavily crippled performance in CL1 test where +12V and 5V went out of voltage regulation limits. Even in the CL2 test, where rails kept their voltages within the limits, +12V dropped very low compared to the full load test.

Efficiency at Low Loads

In the next tests, we measure the efficiency of VP350P at 40, 60, 80 and 100W load. The aforementioned loads represent scenarios in which a typical office PC is in idle with power saving turned on.

Efficiency at the first two tests is pretty low, but still exceeds 70%. In the last two tests, where the applied load is more than the 20% of the unit's max rated capacity, efficiency is close to the 80% mark. Since the unit managed to keep over 70% efficiency the results here are not so bad. If you plan to use it in a system that draws around 80W at idle then you will not suffer great power losses.

5VSB Efficiency

ATX spec states that the 5VSB standby supply's efficiency should be as high as possible and recommends 50% or higher efficiency with 100mA load, 60% or higher with 250mA load and 70% or higher with 1A or more load.
We will take four measurements, three at 100 / 250 / 1000 mA and one with the full load that 5VSB rail can handle.

Efficiency at 5VSB may not be ground breaking but still is fairly good since the unit surpasses the equivalent limits on all load levels. With full load, 2A, efficiency peaks at 75.11%.

Power Consumption in Idle & Standby

In the table below you will find the power consumption and the voltage values of all rails (except -12V), when the PSU is in idle mode (On but without any load at its rails) and the power consumption when the PSU is in standby (without any load at 5VSB).

In both idle and standby, power consumption is low. With only 0.16W phantom power the PSU passes the ErP Lot 6 requirements, 2010 and the future 2013 ones, with flying colors.