Our testing procedures can be found at this link.
The 10pc load equates to 65W of load - it's not an exact figure as the various lines have to be loaded with particular amps/volts that may not exactly map out to the desired number.
The efficiency figures are good, especially at super-low load, which is important when you consider a mid-range system idles at less than 65W. The supply maintains a 90 per cent-plus efficiency from 200W onwards, keeping it up right until the maximum continuous figure is reached.
In terms of regulation, we're looking at just how well the supply is able to hold to the various lines. The ATX spec. has a +/- 5 per cent leeway on all but the -12V line.
|10 per cent||+1.4pc||+0.9pc||+1.1pc|
|50 per cent||-1.2pc||-0.8pc||+0.3pc|
|100 per cent||-2.4pc||-2.0pc||-0.2pc|
The supply performs well when hit with various loads. As is the norm, the lines ride a little high with little or no load, falling just under ideal at around 50 per cent load. Given that most of modern PCs' workload tends to focus on the 12V line, the regulation is very good.
Regulation - cross-load
How about providing uneven loads that stress particular voltage rails? In the first attempt, we've put 48A on the 12V rails, and 1A on the 3.3V and 5V rails. This can actually be somewhat typical for a system heavy on graphics and CPU power. In the second, we've turned the tables and gone for 15A on both the 3.3V and 5V rails - highly unlikely in a real-world environment - and just 2A on the 12V - even more unlikely!
|Cross-load 12V focus||+1.0pc||+0.2pc||-0.9pc|
|Cross-load 3.3V/5V focus||-2.3pc||-1.8pc||+0.4pc|
Hammering one part of the PSU while using just a smidgen of the other can throw cheaper supplies of out kilter. There are no such problems here. The be quiet! 650W model is very good/excellent at keeping voltages nice and smooth, irrespective of the type of load.
|Line/Load (mv - p-p max)||3.3V||5V||12V|
|10 per cent||10mV||15mV||30mV|
|50 per cent||15mV||20mV||35mV|
|100 per cent||15mV||20mV||55mV|
The ATX v2.2 spec states that the maximum permissible ripple is 120mV for the 12V line and 50mV for others.
PSUs convert AC power into DC, but doing so requires the AC waveform to be suppressed. What we're really testing here is the quality of the supply's rectifier and any smoothing capacitors in getting rid of this unwanted up-and-down ripple. The supply is pretty capable of removing the noisome ripple from the 3.3V and 5V in particular, though the 12V's isn't the best we've ever seen.
|10 per cent||27°C||34°C|
|50 per cent||31°C||37°C|
|100 per cent||37°C||42°C|
High efficiency ratings tend to go hand-in-hand with low-ish temps; there's not a great deal of heat being created by the PSU. Noise, too, is very low, as the fan is barely audible when the supply's running flat out. We then put the supply into one of our proper PCs and ran a few load-intensive tests. Again, the supply's very quiet at all times. It's only by viewing it spinning that you know it's on. Other supplies are semi-passive; be quiet!'s doesn't need to be.