The test
Our testing procedures can be found at this link.
Efficiency
| Load | 10pc | 25pc | 50pc | 75pc | 100pc |
|---|---|---|---|---|---|
| Efficiency | 87.2pc | 92.4pc | 94.6pc | 92.8pc | 92.0pc |
Efficiency is simply excellent at all levels. Cheaper, lower-quality supplies tend not to do as well with super-low loads - 10 per cent, for example - but we believe that having high efficiency is perhaps even more important at this level. 85W is usually the kind of power-draw, at the mains, that a modern PC idles at. Achieving almost 95 per cent efficiency at a 50 per cent load and above 92 per cent from 25-100 per cent load means it passes Platinum PSU certification.
Regulation
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.
| Line/Load | 3.3V | 5V | 12V |
|---|---|---|---|
| 10 per cent | +0.4pc | +0.9pc | +0.8pc |
| 50 per cent | 0pc | +0.8pc | +0.5pc |
| 100 per cent | -0.8pc | -0.2pc | -0.1pc |
The supply performs very well across all loads. The regulation is never more than one per cent away from ideal: impressive stuff.
Regulation - cross-load
How about providing uneven loads that stress particular voltage rails? In the first attempt, we've put 66A 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!
| Line/Load | 3.3V | 5V | 12V |
|---|---|---|---|
| Cross-load 12V focus | +0.8pc | +0.6pc | -0.3pc |
| Cross-load 3.3V/5V focus | -1.0pc | -0.4pc | +0.6pc |
Hammering one part of the PSU power delivery while using just a small portion of the other can throw cheaper supplies of out kilter. There are no such problems here. The be quiet! Dark Power Pro 10 850W model is excellent at keeping voltages nice and smooth, irrespective of the type of load.
Ripple
| Line/Load (mv - p-p max) | 3.3V | 5V | 12V |
|---|---|---|---|
| 10 per cent | 12mV | 15mV | 15mV |
| 50 per cent | 18mV | 20mV | 20mV |
| 100 per cent | 20mV | 22mV | 26mV |
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. 12V suppression is very, very good and way, way below (read better) than what the ATX spec. mandates.
Temps
| Temperatures | Intake | Exhaust |
|---|---|---|
| 10 per cent | 26°C | 29°C |
| 50 per cent | 31°C | 35°C |
| 100 per cent | 38°C | 40°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. Going against the grain of commentary on the first page, perhaps be quiet! should think about switching off the fan at low loads; the supply, rated to perform within specifications at 50°C, can certainly handle it.
