Testing Methodology

If you want to make sure a piece of equipment operates as it should by providing accurate readings, you only have to compare its readings with those of a similar tool that is calibrated properly and accurate. This is exactly what I did with PassMark's PSU tester as I compared it to the Faganas ATE station I use to conduct my PSU reviews. The Faganas ATE consists of the following parts:

2x Chroma 63601-5 mainframes
1x Chroma 63600-2 mainframe
10x Chroma 63640-80-80 electronic loads
1x Chroma 63610-80-20 electronic load
1x Keysight AC6804B AC source
1x Keysight DSOX3024A oscilloscope
1x Picoscope 4444 differential USB oscilloscope
1x N4L PPA1530 power analyzer
1x Picoscope TC-08 temperature logger
1x LabJack U3-HV voltage and PWM logger
1x UNI-T UT372 tachometer
1x Keithley 2015 - THD multimeter
1x 3 KVA transformer

The cost of my test system's hardware exceeds US$50,000, while the in-house-developed software—a work in progress for almost ten years now—is priceless.

The power supply I used for all tests was a Super Flower SF-650F14RG. I conducted all tests using the Chroma setup, and I conducted all tests again with the PassMark PSU tester installed between the electronic loads and the power supply.

Results - 12 V1 and 12 V2 Rails

Voltage readings are accurate enough, and the same goes for the amperage readings at 12 V2. At 12 V1, the amperage readings are not that accurate, while the ripple readings are way too high. PassMark used the capacitors the ATX specification requires, 0.1μF ceramic disk capacitors and a 10 μF electrolytic capacitor, to simulate system loading, so the differences might be due to the measurement technique and the different ripple measurement circuits. We use high-end differential scopes that cost four times as much as PassMark's tester.

Results - Minor Rails

Voltage deviations are low at 5 V and not high at 3.3 V as long as the loads are kept low on this rail. The amperage readings are not very accurate at 5 V and 3.3 V, and the same goes for the ripple readings. Finally, both voltage and amperage readings at 5VSB are very accurate, which is a pleasant surprise. Unfortunately, the PassMark PSU tester doesn't check ripple at 5VSB.

Results - Power Measurements

The power measurement is a bit off with the light load (10% of the PSU's max-rated-capacity), but with heavier loads, it becomes more accurate, reaching a very low deviation of only 0.21% at full load.

Results - PSU Timings

The differences here are not significant. This is a great tool to measure various PSU timings. The only problem is that measuring the T6 (PWR_OK inactive to DC loss delay) timing the way the ATX specification requires takes applying the full load to the power supply.

Results - Slew Rate

Small differences in the slew rate readings, especially at +12 V.