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Review: XFX 850W ProSeries XXX Semi-Modular Bronze PSU

by Tarinder Sandhu on 12 October 2012, 09:03 4.0

Tags: XFX (HKG:1079)

Quick Link: HEXUS.net/qabnnf

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Testing results

Our testing procedures can be found at this link.

Efficiency

Load 10pc 25pc 50pc 75pc 100pc
Efficiency 79.4pc 85.2pc 87pc 84.9pc 83.6pc

80 PLUS Bronze-rated supplies need to be 82 per cent efficient at 20 per cent load and at least 85 per cent efficient at 50 per cent load. The supply manages to exceed these figures when evaluated from a 230V source. Indeed, it gets reasonably close to attaining the 80 PLUS Silver 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 +1.6pc +1.3pc +1.3pc
50 per cent +0.2pc +0.5pc

+0.2pc

100 per cent -1.9pc -1.2pc -1.5pc

The supply performs well across all loads. The worst-case scenario is on the 3.3V line, surprisingly, with best-to-worse regulation of 3.4 per cent.

Regulation - cross-load

How about providing uneven loads that stress particular voltage rails? In the first attempt, we've put the 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 +1.8pc +1.6c -1.2pc
Cross-load 3.3V/5V focus -1.9pc -1.3pc +1.0pc

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 XFX supply is pulled and pushed a little more as we focus on particular lines. Again, there's nothing here that stands out as a red flag; it's all within specification.

Ripple

Line/Load (mv - p-p max) 3.3V 5V 12V
10 per cent 10mV 10mV 15mV
50 per cent 10mV 10mV 20mV
100 per cent 15mV 15mV 30mV

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 good - surprising so, actually - and way, way below (read better) than what the ATX spec. mandates.

Putting it into context, we've rarely seen better ripple suppression on Platinum-rated supplies costing twice as much.

Temps

Temperatures Intake Exhaust
10 per cent 26°C 30°C
50 per cent 30°C 39°C
100 per cent 40°C 47°C

Charged with producing 85W at the lowest-load setting the PSU is barely ticked by the 10 per cent load figure. Give it some proper load - 50 per cent - and it remains fairly cool. The casing never becomes warm to the touch, even when running full-pelt, so while the 47°C figure may seem high on first glance, it's nothing that we'd worry about.

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.

Load Fan RPM Airflow Noise
10 per cent 601rpm 20.7cfm Quiet
50 per cent 825rpm 26.1cfm Quiet
100 per cent 1,200rpm 46.0cfm Semi-quiet

The fan controller is in charge of ensuring that the 135mm ADDA fan doesn't shriek like a banshee when under load. The fan is just about noticeable at low loads. At 50 per cent load it emits a faint hum that should be masked by other components in the system. Run at top speed and the whooshing sound is noticeable, but not so much so that it becomes annoying. There are quieter supplies out there, granted, yet run at medium-capacity levels and we're confident you won't hear it above other fans in the system... unless you have a penchant for super-low-noise operation.