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.
Our hold-up time tests are described in detail here.
The measured hold-up time is only 0.5ms lower than the minimum allowed. However, the power-good signal's hold-up time is 2.7ms less than 16ms, which is what the ATX spec requires. In other words, the PSU fails here. The only silver lining is that the power-good signal drops well before the rails go out of spec.
For details on our inrush current testing, please click here.
The inrush current is at normal levels for a PSU with 850W capacity.
Load Regulation And Efficiency Measurements
The first set of tests explores voltage rail stability and efficiency. The applied load equals (approximately) 10 to 110 percent of the supply's maximum 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 a PSU is Haswell-ready or not. In the second test, we determined the maximum load the +12V rail could handle with minimal load on the minor rails.
|Test #||12V||5V||3.3V||5VSB||DC/AC (Watts)||Efficiency||Fan Speed (RPM)||Noise (dB[A])||Temps (In/Out)||PF/AC Volts|
Load regulation is very tight on all rails, taking the lead from many PSUs in this competitive category. Moreover, the PSU operates passively at up to the 40 percent load test, generating zero noise. The fan kicks in at 50 percent, but spins slowly, creating minimal acoustic output. We had to dial in 90 percent of this PSU's max-rated load to make the fan spin faster, and only under a full load does the fan spin as fast as it can. At that point, noise output is around 52.3 dB(A).
With 20 percent load, the 850 P2 clears the 80 Plus Platinum requirement of at least 90 percent efficiency. But it's 0.56 percent shy of doing this with 50 percent load. Under full load, it doesn't reach the 89 percent goal (but it's really close). We'll remind you, though, that the 80 Plus organization tests at a much lower ambient temperature, so we expect to see lower efficiency across our suite. The higher the operating temperature of a PSU, the greater the impact on efficiency.