ProsAmazing "power-to-weight" ratio; ultra-quiet at idle despite no zero-fan mode; very efficient
ConsDespite new larger fan, still loud under heavy loads; short warranty
Here at The Tech Buyer's Guru, we take a slightly different approach to reviewing power supplies. We don't have (and do not intend to purchase) the advanced load testing equipment required to assess the electrical properties of power supplies. In part that's because we only review high-end, high-quality units (read: no bargain-basement offerings!), so we operate under the assumption that these units will conform to their specifications and pass all the required efficiency, voltage regulation, and hold-up time tests required to achieve their particular "80 Plus" certification. In fact, unlike so many other components in the PC industry, power supplies are actually very well regulated, which means it's hard to get a real lemon. And that's a good thing, because a bad power supply can take down an entire system pretty quickly.
So in this review of the new SilverStone SST-SX500-G SFX Power Supply, we're going to focus on relative efficiency, fan operation, noise, ease of use, and overall value. The last power supply we reviewed was SilverStone's SX700-LPT 700W Platinum-rated SFX-L power supply. Offering up 700W and Platinum efficiency in an extended SFX format, it was very impressive, but it also came at a steep price. SilverStone is targeting the new SX500-G at a much broader market, and it's likely hoping it will sell in much greater numbers. It's a major update to the old ST45SF-G 450W Gold model, which has been around for what seems like ages (OK, five years to be exact), and was among the very first modular SFX units ever released. We view the SX500-G as the replacement for that model, but perhaps for the extended SX500-LG as well, which helped pioneer the SFX-L format when it launched in early 2015. We'll be using the SX500-LG V2 as the reference model for our testing in this review.
We'd like to extend a special thank you to SilverStone for providing us a review sample of the SilverStone SX500-G.
Description and Features
First off, being an SFX power supply, which is tiny, at just 125mm wide, 63.5mm tall, and 100mm long. The only dimension that differs from SFX-L models, like the SX500-LG that we'll be comparing it to throughout this article, is in length; SFX-L models are 130mm long, which allows them to use 120mm fans. To bridge the difference without enlarging the chassis, the SX500-G moves from the 80mm fans used in SilverStone's previous SFX units to a larger 92mm fan, which marks the biggest visual difference in this model.
Interestingly, despite being a pioneer in the SFX arena, SilverStone was not the first manufacturer to jump up to 92mm fans in SFX power supplies. That honor goes to Corsair, which released its class-leading SF450 and SF600 back in March of 2016. SilverStone actually showed off a prototype of its competing unit earlier, at CES in January 2016, and you can see a photo of this prototype in TBG's coverage of the event. Alas, it's taken a year and a half to bring it to market, and according to SilverStone's representative Tony Ou, part of the delay came down to SilverStone working very closely with OEM manufacturer High Power to make sure that the SX500-G surpassed the performance of Corsair's offerings.
Of course, the SX500-G also needed to contend with its in-house competition, in the form of the SX500-LG (the 5-year-old 450W and 600W SFX units are really no longer viable alternatives, from our point of view). The SX500 improves upon its larger cousin in a number of ways. First, it has 41.7A on the 12V rail versus 40A, for a true 500W on the 12V rail (up from 480W). That translates to an amazing 630W/liter, up from 484W/liter. It also has enhanced over current protection, as well as vastly improved connectors. The one that stuck as most interesting is the 4-pin "Sense" input, and we'll let SilverStone explain this one:
The separate 4pin sense connector is to improve voltage regulation. Without it, the PSU will still work fine but regulation will drop by about 1% ~ 2%, not a big deal for 99% of users but matters a lot in PSU reviews where a couple of percentage points could mean the difference between first place on the chart and middle of the pack.
As we said in the introduction, we don't actually test things like voltage regulation, but we wanted to point this out to show just how far SilverStone has gone to move the SFX standard forward.
The SX500-G also adds a third SATA/peripheral output, allowing it to power a total of six SATA devices and three peripheral devices simultaneously. Instead of one PCIe cable with dual 6+2 pin connectors, it has two PCIe outputs, with each cable having just one 6+2-pin connector. This change makes sense given that Nvidia has moved to the 8-pin standard for many of its latest video cards, rather than dual 6-pin connectors (both are capable of supplying 75W). Thoughtfully, SilverStone has put one of these PCIe connectors on a 400mm cable, while the other is on a 550mm cable. This corresponds to the reality than in an SLI setup, one video card is always going to be further away, and more importantly, that most SFX power supplies are used in ITX systems, where a shorter cable is actually an asset. Below you can see all of the cables included with the SX500-G, minus the floppy/Berg connector that we're sure no one will be using!
Of note, the SX500-G doesn't have a "zero-RPM" or "hybrid fan" mode, which would allow the fan to turn off at very low loads. Interestingly, the Corsair SF series, which uses a similar 92mm fan, does have this feature, and its fan only turns on when power draw reaches 20%. Our guess is that SilverStone determined that the frequent noise fluctuations caused by surpassing a similar threshold (100W in the case of the SF500-G) would be more distracting to the user than simply keeping the fan spinning at all times. Update: SilverStone has confirmed to us that avoiding the constant on/off cycling reduced perceived noise for the user.
In a chassis as small as the one used for SFX units, this is probably the safest approach - there's just not a lot of room for heat to dissipate on its own otherwise. Alas, there may be another reason for this approach. We're sorry to have to bring this up, but SilverStone has had a bit of a rough go of it when it comes to zero-fan RPM modes. The original SX500-LG SFX-L unit offered this feature, but it turned out to be defective. The fan would engage at an RPM level that was under its rated range, meaning it was operating below proper voltage, causing it to tick wildly. User reports and complaints ran rampant on the Internet, and SilverStone eventually caught on to the problem and updated the SX500 to version 2, which eliminated the zero-RPM mode. While this did indeed lead to an improvement in the overall noise profile (we RMA'd our original-issue SX500-LG for a v2 model), the fan was unfortunately not particularly quiet at its lowest rated RPM level, which is probably what got SilverStone in that mess in the first place.
One last thing we should mention is the warranty. While SilverStone has not yet published a warranty for the brand-new SX500-G, based on the precedent set by other Gold-rated models, we expect it to be three years. This seems a bit short in light of the "warranty arms race" currently gripping the PSU industry, with many major players bumping their standard warranties up to ten years. As some commentators have mentioned, doing so on a component that undergoes significant stress and can be abused by certain users (read: cryptocurrency miners) comes with its own risks, namely inundating RMA departments with potentially improper warranty claims. That being said, we do hope SilverStone will choose to back this unit up with a 5-year warranty, which it applies to its Platinum and Titanium product lines. We believe that this would be reasonable given this unit's pricepoint and the fact that it's an unlikely candidate for an extreme gaming or mining rig. Update: SilverStone has confirmed to us that the SX500-G is covered by a 3-year warranty.
OK, flip to the next page to see our performance-related metrics and conclusion!