Load Regulation, Hold-Up Time And Inrush Current
To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units.
Primary Rails And 5VSB Load Regulation
Load Regulation testing is detailed here.
The following charts show the voltage values of the main rails recorded over a range from 40W to the maximum specified load, and the deviation (in percent) for the same load range. You will also find a chart showing how the 5VSB rail deals with the load we throw at it.
Our hold-up time tests are described in detail here.
The hold-up time was right on target at 16ms. While a larger APFC cap can offer prolonged hold-up time, it also affects efficiency and increases the PSU's cost, so it's preferable to use the corresponding component in this section.
For details on our inrush current testing, please click here.
The registered inrush current was much higher than we expected. We would like to see lower readings with both 115V and 230V input.
Load Regulation And Efficiency Measurements
The first set of tests reveals the stability of the voltage rails and the PSU's efficiency. The applied load equals (approximately) 10 to 110 percent of the maximum load the supply can handle, in increments of 10 percentage points.
We conducted two additional tests. During the first, we stressed the two minor rails (5V and 3.3V) with a high load while the load at +12V was only 0.10A. This test reveals whether the PSU is Haswell-ready or not. In the second test, we determined the maximum load the +12V rail could handle while the load on the minor rails was minimal.
The output noise stayed at low levels at up to the 40-percent load test, and only exceeding the 40 dB(A) mark when we dialed in a 375W load. At higher loads and under really tough conditions, the fan's noise will be annoying for many users. This could have been avoided if Fractal Design used a larger-diameter fan capable of pushing the same amount of air, but at lower speeds.
In the load regulation area, the +12V and 5V rails were within two-percent deviation. The 3.3V rail didn't do as well; it exceeded three percent. While we would like to see all rails within two percent, this isn't a high-end platform, so the pursuit of top performance wasn't the first priority of Fractal Design's designers.
According to the 80 PLUS Gold certification, efficiency should meet or exceed 87 percent at light load, 90 percent at typical load and 87 percent at full load. What the 80 PLUS organization means is 20 percent, 50 percent and 100 percent of the unit's max-rated capacity at typical and full loads. As you can see from the table above, the Edison M 750W PSU doesn't quite meet the minimum requirements with typical and full load. We should stress however, that the 80 PLUS tests are conducted at much lower operating temperatures, allowing for higher efficiency levels.