Testing
Testing — Physical Weight
One of the basic measures of any ATX power supply is the unit’s overall physical weight. This may seem rather simplistic but it generally holds that more components and larger heatsinks equal a better PSU.
Testing — DC Output Voltage Load Regulation
To simulate real world operation, the BFG Tech 600W PSU was connected to my home made load tester, supplied with 115 VAC, and allowed to burn-in for 24 hrs before voltage readings were taken. In this test we are interested in seeing how well a PSU can maintain the various output voltages while operating under different loads. The DC output voltages were measured with a FLUKE digital multimeter.
The new ATX12V V2.2 tolerance for voltages states how much each output (rail) is allowed to fluctuate and has tighter tolerances for the +12V1 and +12V2 outputs.
The following table lists the DC voltage results at different loads for the BFG Tech 600W PSU while operating on 115 VAC, 60 Hz.
The BFG Tech 600W PSU produced average-to-good voltage regulation on all of the outputs across a broad range of loads. The +12V output readings are within the older ±10% tolerance but are not held within the new, tighter ±5% tolerance.
The only time the +12V2 rail was loaded (11.6A, 140 watts) was during the final 471watt combined load test, when it dropped to 11.88V.
Testing — AC Ripple (electrical noise) on DC Outputs
The amount of AC ripple present on the outputs was checked using an oscilloscope. This AC component may be present in the KHz range where most switching power supplies operate or it may be more prevalent at the 60 Hz line frequency. I adjusted the O-scope time base to look for AC ripple at both low and high frequencies.
The new ATX12V V2.2 specification for DC output noise/ripple is defined in the ATX12V Power Supply Design Guide. However, BFG Technologies specifies 75/150 mV instead of 50/120 mV.
Ideally we would like to see no AC noise on the DC outputs — the cleaner the better! But in reality there will always be some present. I measured the amplitude of the AC signal (in millivolts, peak-to-peak) to see how well the power supply complied with the ATX standard. The following table lists the ripple/noise results during our 263 w load test for the five main output voltages of interest.
The BFG Tech 600W power supply exhibited good AC ripple suppression on all of the measured outputs, which was well within the ATX12V V2.2 specification.
