Review: be quiet! Pure Power L8 630W PSU

Testing results

Our testing procedures can be found at this link.

Efficiency

The 10pc figure equates to around 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 very solid from the usual 25-100 per cent range, with the supply not dipping below 85 per cent at any point. Put it another way, the supply grabs 360W from the wall to provide 315W to the components, compared with around 345W required for a more-expensive 80 PLUS Gold-rated model. It would take a long time to recover the initial extra outlay for a better-specified supply, then.

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.

The standard that most PSU-makers look towards when referencing line regulation is a +/- 3 per cent leeway. This £60 supply manages that on all but the 3.3V line, and it's only by straining it to the limit that deficiencies are noted. Do understand that it's irregular to load the 3.3V line to 100 per cent capacity in real-world usage; the 12V line's performance is much more important.

Regulation - cross-load

How about providing uneven loads that stress particular voltage rails? In the first attempt, we've put 45A 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!

Hammering one part of the PSU while using just a smidgen of the other can throw cheaper supplies of out kilter. There are no major problems here. The be quiet! 630W model's regulation becomes a little looser when pushed and pulled, but it remains firmly within specification.

Ripple

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 Pure Power 630W's performance is excellent in this regard, more so once the price and value are factored in.

Temps

Fan performance

Temps are good but they mean little in isolation. Obtaining accurate noise readings is near-on impossible when the supply is connected to the Chroma test harness and dual-unit load-tester. We can test the manufacturer's quietness claims in a different way, by using an AMPROBE TMA10A anemometer placed directly over the centre of the PSU. The anemometer records the airflow being pushed/pulled from the PSU's fan. We can use a Voltcraft DT-10L RPM meter to measure the rotational speed of the fan, too.

We can then provide the fan RPM, airflow and, on a subjective level, the noise level of the PSU - undertaken rather (un)scientifically with the age-old ear-next-to-fan methodology.

The fan remains practically silent at up to 50 per cent load, pushing little airflow. Ramp it up to maximum, which is unlikely for long-term use, and, while speeding-up, it remains quiet. On a more pragmatic note, run around 250W load, which is indicative of a decent system's power-draw when playing games, and the PSU's fan certainly won't be heard above the other components in a system.