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 industrial grade components and larger heatsinks equal a better PSU. The following graph illustrates how the Toughpower 850W PSU compares to some other popular power supplies on the market.
(click to enlarge)
DC Output Voltage Load Regulation
To simulate real world operation, the Thermaltake power supply was connected to the load tester, supplied with a constant 115 VAC input, 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 under a moderately heavy load. The DC output voltages were measured with a FLUKE digital multimeter at the ATX connector.
The ATX tolerance for voltages states how much each output (rail) is allowed to fluctuate.
The following table lists the DC voltage regulation results for the Toughpower 850W PSU.
As you can see, all of the DC outputs were held well within the ATX specification while operating under a wide range of combined loads, all the way up to 850 watts — this is excellent load regulation!
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. In each case, I adjusted the O-scope time base to look for AC ripple at both low and high frequencies. The ATX specification for DC output noise/ripple is defined in the ATX12V Power Supply Design Guide.
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 Toughpower 850W power supply exhibited good AC ripple suppression on all of the measured outputs except for the +12V rails at maximum output. I can’t be too hard on Thermaltake for this because it’s not realistic to expect anyone will actually run a PSU in a real PC at the maximum rated load.