Review Index:

SilverStone 500W SFX-L Series Power Supply Review

Manufacturer: SilverStone

Introduction and Features


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SilverStone has a long-standing reputation for providing a full line of high quality enclosures, power supplies, cooling components, and accessories for PC enthusiasts. With a continued focus on smaller physical size and support for small form-factor enthusiasts, SilverStone recently introduced the new SX500-LG. There are currently five power supplies in the SFX Series, ranging in output capacity from 300W to 600W. The SX500-LG is the first one to feature an extended chassis. The SX500-LG enclosure is 30mm (1.2”) longer than a standard SFX chassis, which allows using a quieter 120mm cooling fan rather than the typical 80mm fan used in most SFX power supplies.

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150mm                                130mm                              100mm

The new SX500-LG SFX-L Series power supply was designed for small form factor cases but comes with an ATX adapter plate so it can be used in a standard ATX enclosure as well. In addition to its small size, the SX500-LG features high efficiency (80 Plus Gold certified), all modular flat ribbon-style cables, and provides up to 500W of continuous DC output. The SX500-LG PSU also operates in semi-fanless mode (cooling fan turns off at low power).

Note: We have seen rumors on the web about the new SX500-LG power supply being a re-packaged version of the SX600-G that SilverStone recalled awhile back. Rest assured it is not. The SX600-G is a completely different PSU made by Enhance and the new SX500-LG is made by High Power. And yes, the SX500-LG is officially listed as an 80 Plus Gold certified PSU (10-22-2014).

Here is what SilverStone has to say about the new SX500-LG PSU: “For small form factor enthusiasts, the standard SFX power supply form factor has an excellent combination of size, power, and affordability. At 100mm deep, however, the standard SFX PSU is also limited in fan size to 80mm. While advances in engineering and components have modern high-end SFX PSUs quieter than ever, there is still inherent limitation with 80mm fan’s ability to dissipate heat at maximum loading conditions while maintaining satisfactory noise profile for users sensitive to higher-pitch sounds. With this in mind, SilverStone has released a “lengthened” variation of the SFX form factor called, SFX-L. With 30mm of added depth, a SFX-L power supply has enough room to fit a 120mm fan, thus its maximum load noise can be not only lower in intensity (via slower fan speed), but also lower in pitch (due to larger fan size). The first model to debut in the SFX-L will be the SX500-LG, a 500W model that includes all features available from top of the line SFX SilverStone PSUs such as 80 Plus Gold efficiency, modular flexible flat cables, and semi-fanless capability. An ATX adapter bracket is included as well to enable users to install this PSU into any small or even larger cases that do not have SFX mounting holes.

SilverStone SX500-LG V1.1 SFX-L Series Power Supply Key Features:

•    New SFX-L form factor (and ATX via included adapter)
•    Silent running 120mm fan with intelligent semi-fanless operation
•    500W Continuous DC output (up to 40°C)
•    High efficiency with 80 Plus Gold certification
•    100% Modular cables, flat ribbon-style
•    Strict ±3% voltage regulation with low AC ripple and noise
•    All Japanese made capacitors for reliable operation
•    Powerful single +12V rail with 40A (480W)
•    Two PCI-E 6+2 pin connectors
•    Protections: UVP, OVP, OPP, and SCP
•    Universal AC input and Active PFC
•    MSRP $99.99 USD

Please continue reading our SilverStone SX500-LG power supply review!!!

PSU Testing Methodology

Establishing an accurate load is critical to testing and evaluating a PC power supply.  PCPerspective’s power supply test bench can place a precise DC load on the PSU under test.  Each power supply is tested under controlled, real-world conditions up to its maximum rated load (at 40ºC), using both 115 VAC and 240 VAC line voltage.  Our current suite of tests includes:

•    DC Load Regulation
•    AC Ripple and Noise
•    Efficiency
•    Differential Temperature
•    Noise

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The SilverStone SX500-LG power supply was evaluated on both features and performance.  A full range of equipment was used to test the power supply under controlled load conditions.  

•    (2) CSI3710A Programmable DC load (+3.3V and +5V outputs)
•    (4) CSI3711A Programmable DC load (+12V)
•    (3) 218W Precision resistor load bank (+12V)
•    Switchable precision resistor load bank (-12V and +5VSB)
•    Agilent 34401A digital multimeter (Accuracy ±0.0035% vDC)
•    Extech 380803 Power Analyzer (Accuracy ±0.5% of full scale)
•    DS1M12 "StingRay" digital oscilloscope (20M S/s with 12 Bit ADC)
•    Powerstat Variable Autotransformer, 1.4 KVA, 0-140 VAC
•    Extech Model 407738 digital sound level meter (Accuracy ±1.5 dB)

The following cables/connectors were used to connect the SX500-LG to the PCPerspective power supply test equipment.
•    (1) 20+4 pin ATX
•    (1) 4+4 pin EPS/ATX12V
•    (2) 6-pin PCI-E
•    (2) SATA
•    (2) Molex

Video News

April 28, 2015 | 03:43 AM - Posted by Anonymous (not verified)

An important thing to note about the 'fanless' mode: The entirety of the fan control system is composed of a thermistor attached to the internal heatsink that controls fan voltage, and Silverstone using a fan which happened to have a startup voltage that worked well with the voltage produced by the thermistor and desired startup temperature. The problem being that it is an entirely dumb control system, with only the thermal load of the heatsink (or rather, the thermistor strapped to the heatsing with a short length of heat-shrink tubing) providing any hysterisis.

The upshot being that under idle/low-load conditions, the fan will tend to hover just at the startup voltage. Unfortunately, the fan will also make a lot of noise in this regime, with clicks coming from startup/shutdown and buzzing just below startup as energy is dissipated into the rotor sufficiently to produce audible vibration but insufficient to overcome static friction and start the rotor moving.

Sadly, this makes the PSU in practice a lot noisier than it should be. Infuriatingly, without the 'fanless mode' the PSU would be really quite silent. Silverstone (via Tony Ou on the HardOCP forums) even tried their own slim 120mm fan, [url=]and rejected it doe to not spinning down[/url], meaning the PSU is semi-fanless at the expense of actual low-noise operation!

There are quite a few other PSU sellers using the same Sirfa platform that Silverstone are using here, and with different fans, so if they avoid the 'semi-fanless' mode those should in practice be quieter. Or the SX500-LG could be modified with Silverstone's own fan if you're willing to void the warranty (the fan is soldered to the PSU PCB). Option 3 would be to strap a thick 120mm fan to the outside to keep the PSU cool enough that the thermistor never gets hot enough for the fan to approach the startup voltage in the first place.

April 29, 2015 | 12:41 PM - Posted by Anonymous (not verified)

I've replaced the stock fan in my SX500LG with the Silverstone FW121 that Tony Ou used. It's not perfect as the fan still has a quiet buzzing/chatter while spinning, but it's a good improvement over stock.

Also the stock Globefan was not soldered down. It used a 2 pin fan plug+socket, with some sort of glue on top (not engulfing) to secure it.

My next plan is to swap the FW121 for a Scythe Slip Stream SY1225SL12M as it has a very low starting voltage, although this is a full thickness fan that will need to be mounted to the outside.

October 9, 2015 | 04:28 AM - Posted by Gen-x1 (not verified)

I recently purchased this power supply and it's installed in my Xigmatek Nebula ITX case with Z97 mobo, 4690k, GTX970 ITX and even while gaming (Shadow of Mordor - high/ultra settings for example) the fan on the psu still doesn't spin up. I figured out that because my case has negative air pressure, air is being drawn in from the rear of the power supply keeping it cool enough so it never gets to the target temperature for the fan to kick in - making it passively cooled. Fantastic power supply - I'd just rather it didn't use semi fanless mode as the Nebula case is designed so that the psu aides the removal of warm air. My case, GPS and cpu temps are all fine, I just think they'd be a little lower with the extra exhaust provided by a spinning psu fan.

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