be quiet! SFX L Power 500w Review (2)


A power supply is an integral component in any system, for the reason you are probably thinking. A power supply delivers power to the components from the inlet on your power mains and allows your components to do their thing! There are the power supplies that do this job well, efficiently and properly and there are those units that are essentially cheap fireworks, so finding the right one for your system’s needs is paramount for smooth operation.

Aside from the above, there are different sizes and form factors of power supplies on the market. We have the regular ATX sized units designed for low powered desktops, all the way to the quad SLI power hungry gaming systems everyone has fallen in love with over the years… but what about the smaller form factors? Well, competition has increased lately with more and more brands releasing their own SFX power supplies onto the market, but be quiet! has just thrown 2 more onto the scene in the way of the SFX-L Power 500 and 600w power supplies.

Today we will be taking a closer look at the 500w model and giving it the once over…


Size SFX-L – with ATX adapter bracket
Edition SFX L Power
Wattage 500 W
80 PLUS Certification 80 PLUS Gold
Max. Efficiency 92 %
Cooling Fan
Fans 1 x 120mm
Internal +12V Rails Single Rail
Rail 1 +12V 41.7 A
Rail 2 +12V N/A
Rail 3 +12V N/A
Rail 4 +12V N/A
Rail 5 +12V N/A
Rail 6 +12V N/A
Max. Combined Output +12V 41.7 A
Modular Yes
Modularity Full Modular
SLI/CrossFire Yes
EPS 12V Yes
Motherboard Connector 20+4-pin
  • 1 x 4+4-pin CPU +12V (EPS)
  • 3 x 4-pin Molex
  • 4 x 6+2-pin PCIe
  • 6 x SATA
Dimensions 125 x 64 x 130 mm (WxHxD)

Closer Look

Now the main difference between SFX-L and regular SFX is just simply down to size; the reason for the extra size is for improved and more efficient cooling which plays a big part when performance is a key feature. Looking at the SFX-L Power from be quiet! it looks very basic indeed without too much happening, but you must understand that be quiet! is known for their subtle looking, high performance and top build quality throughout their range of products, so I’m not too surprised that all that flashy RGB nonsense hasn’t graced our presence.

be quiet! SFX L Power 500w Review (3)

Cooling the unit down is a single 120mm fan which operates between 8.5db and 28.7db depending on how much load is placed on the unit. Even at 28.7db, it’s not particularly noticeable and with a maximum speed of 1450rpm on the fan itself, it’s understandable why!

be quiet! SFX L Power 500w Review (4)

In terms of specification and design, both the 500w and 600w models are identical aside from the peak power output. The be quiet! SFX-L is fully modular for maximising cable management and it’s nice to see that be quiet! have included 4 x PCIe 8 (6+2) pin cables for multi graphics card set ups; a little overkill, but still nice to have the option nevertheless.

be quiet! SFX L Power 500w Review (5)

Here is a list of the available connectors/cables included inside the box. Note: All the cables supplied with the exception of the mains power cable features a flat cabled design.

1 x ATX 20+4 pin connector
1 x P4+4 pin connector
4 x PCIe 6+2 pin connectors
3 x PATA (Molex) 4 pin connectors
6 x SATA connectors

be quiet! SFX L Power 500w Review (1)

Now that we have seen what the SFX-L Power 500w power supply looks like and what connections it has, let’s see how it does in our testing methodology.


Since we don’t currently have access to an ATE load tester, a multi-meter is used to show each of the power supplies performance on the 3.3v, 5v, and 12v rails. Although we can’t do full load tests, we can provide relative information regarding variance and fluctuation of current and ripple on the rails which is integral and indicative of quality in a power supply.

To perform the above tests, the methodology will be as follows:

Intel Core i7 7700K @ 4.5GHz
ASUS Z270 Maximus IX APEX
Crucial (2x8gb) 16GB DDR4 Ballistix Elite 3000MHz
1 x 525GB Crucial MX300 SSD

Voltages will be monitored via a multi-meter and the AC power draw will be monitored via a power monitor when drawn from the wall. For the idle test, the system will be simply booted up and let to run into windows and after 5 minutes when the power draw has leveled out, the readings will be taken.

To load and apply power to the power supply, a combination of IBT and Furmark will be run to put as much strain on the power supply as possible. After 10 minutes the readings will be taken and to ensure maximum strain, the CPU will be overclocked to 4.5GHz. Depending on the power of the power supply, multiple graphics cards could be used in line with how comfortable I feel the power supply will cope with such load. In the case of this unit, the GTX 1060 doesn’t support SLI. We will endeavor to improve our testing methods throughout 2017.

ATX themselves specify that a fluctuation and variable of 5% is acceptable so to number crunch it means that:

3.3V = 3.135V – 3.465V is acceptable
5V = 4.75V – 5.25V is acceptable
12V = 11.4V – 12.6V is acceptable.

Any readings outside of these figures will be an automatic fail.

3.3V = 3.25V
5V = 5.15V
12V = 12.09V
3.3V = 3.36V
5V = 5.18V
12V = 12.24V


Performance for such a small single railed power supply is good and with an 80PLUS Gold efficiency rating, the numbers should be well within ATX’s specified guidelines; they actually are, but our lack of an ATE load tester with all of the necessary equipment hinders results. We will get one, one day…


SFX is a big deal (mind the pun) and the emergence of smaller, but highly powerful components are growing thanks to the practicality of saving space. Silverstone has probably been at the top end of the consumer SFX power supply market over the last couple of years and other companies have thrown their hats into the ring including Corsair but be quiet! have done so in the way only they could. Let’s digest my opinions and see if it deserves an award, shall we?


Although our testing methodology is rather basic compared to other media, in my opinion, the SFX-L Power 500w performs exactly where it should and if you’ve used be quiet! power supplies over the years, you’ll know how well they are built, how reliable they are and more importantly, how good the overall package is, including warranty etc. If I had to pick any negatives, the only one I can see is the 5V line under load is a little too close to the edge for me, but it’s not a detriment and isn’t particularly important as it’s within the guidelines specified by ATX themselves.


Focusing on the aesthetics, the SFX-L Power doesn’t have much about it and it’s as black and basic as a power supply can be. One interesting thing is be quiet!’s insistence in making the SFX-L Power fully modular which does add an element of desirability, especially when you consider how fully modular has been over the last 5 years… but it’s not the be all and end all as you can’t run a system without the motherboard/CPU power cables anyway! The flat cables throughout is a very nice touch also and makes cable management in tighter spots a lot easier to manage; SFX is small and anything to reduce footprint within an SFX system is always going to be appreciated.

I am however impressed with the build quality and it’s something I have never had to pull be quiet! on throughout any of their range of products.


Currently at the time of writing from Scan Computers, you can pick up the 500w model for £99.98 which is £20 more expensive than Silverstone’s SX500-LG and the specifications are virtually identical, including the 80PLUS Gold efficiency rating. Based on this, it’s hard to see the value for money given the foothold Silverstone has held on the SFX power supply market over the last few years and I would have expected be quiet! to have matched the price, not over throw it like they have done. That being said, the saving grace here is that the 600w model from be quiet! is only £7 more expensive at Scan currently. That makes the 600w a more value effective purchase, but there is now viable competition from many different brands, I just don’t feel the pricing is as good as it can be from be quiet! this time round.

Final Thoughts

The be quiet! SFX-L Power 500w power supply is a good unit and delivers on everything in my opinion other than value. That being said, if you have a strong brand allegiance to be quiet! then the extra £20 isn’t going to bother you much, or at least it wouldn’t bother me. If you are as brand neutral as I am (honest), then Silverstone probably have the leading position here and it does disappoint me a little as I would expect be quiet! to be more aggressive on pricing, just to make a bigger impact. All this being said, the SFX-L 500w is a good power supply and whatever your reasons for making purchasing decisions, you will have still made a smart move picking this for your system over non-reputable brands.

Big thanks to be quiet! for sending a sample of the SFX-L Power 500w in for review.


  • Performance
  • Design
  • Value



– Good build quality throughout
– Flat cables make a lot of sense to use (good job be quiet!)
– Performs well in our testing
– Basic and subtle looks
– More competition is good in the SFX power supply market


– Pricing could be a lot better, especially to compete with Silverstone’s similar models

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