Hot Test Results

Earlier SFX PSU designs were notorious for their poor power quality figures. More recent models, like the SilverStone SX700-LPT and the Enermax Revolution SFX 650W, were greatly improved. Sadly, the electrical performance of the Be Quiet! SFX-L Power 500W may not be as bad as that of the earlier models but it definitely is not on par with these newer designs. Voltage regulation is excellent, with the 12V line maintaining a regulation of 1.1% and the 3.3V/5V lines falling only slightly behind at about 1.5%. Power quality however leaves a lot to be desired. While voltage ripple figures are well within the design guide limits, we recorded a maximum of 82 mV, 42 mV and 36 mV on the 12V, 5V and 3.3V lines respectively, figures that are high by today’s standards and uncomfortably close to the directive’s limits. Paradoxically, when the unit is heavily cross loaded, the main 12V line displays a ripple lower than that of the 3.3V/5V lines.

Main Output
Load (Watts) 100.77 W 250.97 W 374.96 W 498.14 W
Load (Percent) 20.15% 50.19% 74.99% 99.63%
  Amperes Volts Amperes Volts Amperes Volts Amperes Volts
3.3 V 1.71 3.36 4.29 3.35 6.43 3.33 8.57 3.31
5 V 1.71 5.06 4.29 5.04 6.43 5.01 8.57 4.98
12 V 7.15 12.08 17.87 12.03 26.8 11.99 35.74 11.95


Line Regulation
(20% to 100% load)
Voltage Ripple (mV)
20% Load 50% Load 75% Load 100% Load CL1
3.3V + 5V
3.3V 1.5% 12 16 24 36 16 40
5V 1.6% 16 26 30 42 18 42
12V 1.1% 26 42 50 82 76 36


The Be Quiet! SFX-L Power 500W retains its high energy conversion efficiency inside the hotbox, taking only a relatively small performance hit evenly distributed across the entire load range. This indicates that the components are not getting thermally stressed, not even when the unit is heavily loaded under these adverse conditions. The average efficiency reduction is 1.1%, with a drop of 1.5% at 100% load, suggesting that the components are handling the adverse ambient conditions relatively well.

The presence of the 120 mm cooling fan hardly helps the acoustics performance of this PSU when the ambient temperature is very high. It makes the noise levels a little more tolerable when the PSU is heavily loaded, but the PSU will certainly not be quiet under such conditions, not with a load any higher than 100 Watts. Despite the deferential efforts of the cooling fan, the internal temperatures of the Be Quiet! SFX-L Power are relatively high for a PSU with a maximum output of just 500 Watts. With the components not showing any signs of thermal stress and the efficiency holding very well, the obvious culprit here again is the small heatsinks. 

As expected, the heatsinks of the SFX-L Power 500W PSU are too small for extreme operating conditions and, thus, the cooling fan is striving to cope with the high cooling requirements. The internal temperatures are kept at safe levels but the PSU is clearly audible even when lightly loaded, with the fan’s noise reaching intolerable levels  under high loads. As this unit is rated for operation up to 40 °C, we find these results unsurprising.

Cold Test Results (Room Temperature) Final Words & Conclusion


View All Comments

  • u.of.ipod - Monday, November 13, 2017 - link

    Nice review! Any plans to review the new Silverstone SFX models with 500w/650w capacities? Reply
  • jrs77 - Monday, November 13, 2017 - link

    I have the Silverstone SFX-L 500, which seems to be more or less the same PSU as this one. Reply
  • Samus - Tuesday, November 14, 2017 - link

    Ditto. Great PSU. I've had a number of SFX Silverstone PSU's over the years and all have been excellent. Reply
  • MrSpadge - Monday, November 13, 2017 - link

    You're clearly putting effort into the reviews and graphs. Yet you still don't mention the voltage at which the units were tested for efficiency. I know it can be found in that 2014 pipeline post you linked to. But how many readers are not going to look that up and may expect testing at 110 V, because they're from the US, and be disappointed when they find out the good numbers shown by AT don't match their reality? Reply
  • meacupla - Monday, November 13, 2017 - link

    Oh, nice. Someone thought to use a FDB fan in the PSU.

    Other pricey options out there, like Corsair's SF line, still insist on using sleeve bearings, for some reason.
  • Samus - Tuesday, November 14, 2017 - link

    They wanted it to be quiet. They didn't say anything about it lasting more than 50,000 hours ;) Reply
  • PeachNCream - Tuesday, November 14, 2017 - link

    That's still almost 6 years of non-stop operation! (o.O) I'm sure there's cases where people are running decade old power supplies and someone reading the comments will say as much, but if you turn your PC off when you're not using it or just run it for 8 hours a day, 50,000 hours could be like 17 years. Reply
  • Brian_R170 - Tuesday, November 14, 2017 - link

    Not all FDBs are the same (Not sure which one is actually used in the Globe Fan in this PSU) and not all are actually manufactured better than sleeve bearings.

    Corsair's SF-series and Enermax Revolution PSUs with sleeve bearings are semi-passive. For many users, that will translate to lower noise and longer life than an FDB fan that runs all the time. I'm somewhat disappointed that the Be Quiet! doesn't have a semi-passive mode since "acoustics performance is of utmost importance to the company".

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