SilverStone SFX SX650-G 650W Power Supply Review

SilverStone is back with us today with its new small form factor SX650-G. This one has a bigger fan and a few more connectors than the previous models, so we are expecting great results from this SFX PSU. This one clocks in at 819 watts per liter and does carry a gold efficiency rating. Flat shorty cables are stock with tiny builds in mind.


SilverStoneTek is a company best known for its high quality cases but its product lines extend into other components such as cooling, power, fans, storage, and so on. As a company, Silverstone has built up this impressive product repertoire in a very short time having been founded in 2003. Today, however we are interested in its power supplies which are comprised of the Strider, SFX, Nightjar, Gemini, and Zeus model lines that range from 300W to 1500W DC output. For this review, we are looking at one of SilverStone’s SFX units, the SX650-G, which is produced in conjunction with Sirfa.

Sirfa Electronics Co., Ltd. is a name that is not that familiar to most users but Sirfa has been around since 1996 when Sirtec established Sirfa as a factory in the Sirtec group on mainland China. In June 2008, Sirtec sold off its interest in Sirfa making the company independent of the Sirtec brand but still in business with High Power. As such, while we have not seen any Sirfa produced power supplies under the Sirfa brand, some of the Sirtec units of the past were produced at the Sirfa facility. Additionally, we have seen Sirfa providing OEM services for Thermaltake, Enermax, PC Power & Cooling, Tuniq, Lepa, SilverStone, and others with very mixed results.

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A Little Stretch from 500W to 650W; Is It Too Far?

When it comes to SFX/SFX-L power supplies the brand who immediately jumps to our minds is SilverStone. Over the years, we have not seen a lot of these smaller form factor units relative to the number of ATX/EPS units we have seen but when we have there is a good chance they have been from SilverStone. So, today, it is somewhat unsurprising that we are back at it again with another SFX unit from SilverStone in the guise of the SX650-G. At 650W this is the largest capacity SFX unit we have seen from SilverStone and it matches the largest capacity SFX unit we have seen from anyone else. That said, SilverStone has done quite well in this segment from a quality standpoint (and from an innovation standpoint) in the past. So, today, we would expect that this step up in capacity should be no big deal. But is it? Before assuming too much about this unit, let's see what SilverStone has to say about this specialty item:

After pioneering full featured, high performance SFX power supplies in 2012, SilverStone has continued refining the segment it has created. The SX500-G and SX650-G are yet another evolutionary step toward perfecting this small form factor power supply category. They are more powerful without growing in size to achieve class-leading power density levels of 633W per liter for the SX500-G and 818W per liter for the SX650-G. This increase in power density was achieved through more advanced engineering and component selection so rather than added noise as is the norm for upping wattage output in power supplies, the SX500-G and SX650-G are quieter than their less powerful predecessors. Their noise signature was further lowered thanks to the use of 92mm fans versus 80mm on previous models. For connectivity, the SX500-G and SX650-G are equipped with more connectors so they can be used in wider variety of system configurations. SilverStone’s famed short, flexible flat cables will of course be part of the package as well (a longer standard length cable set, the PP05-L is available for purchase separately). For those looking for the best bang for the buck in high performance SFX power supplies, the SX500-G and SX650-G will not disappoint.

Let’s move on and see what we can expect when a user purchases the SX650-G power supply at retail in terms of documentation, accessories, cable count, rail layout, output characteristics, and general build quality.