The new SX500-G is a good power supply, especially for the standards of this form factor, where ultra-compact dimensions impose many limitations. Its performance is admirable, exhibiting tight load regulation on all rails, a long hold-up time, an accurate power-good signal, and strong ripple suppression at +12V. On top of those strengths, the fan profile appears to be tuned well; despite the lack of a semi-passive mode, the SX500-G still achieves low noise output. Of course, once you push hard, the fan starts spinning a lot faster, making its presence felt. Even then, though, noise doesn't exceed 40 dB(A).
If you need a small PSU, be prepared to make some compromises when it comes to noise. After all, overpopulated platforms have a hard time maintaining low operating temperatures, especially under tough conditions and taxing loads. With such high power density scores, keeping the PSU at normal temperatures inside isn't easy.
SFX-based PSUs also command premium prices. Unfortunately, when it comes to power supplies, smaller sizes and better performance means more costs.
We uncovered a number of issues with the SX500-G. For starters, we don't like the 85°C-rated bulk cap. In such a compact PSU, where the internal temperatures are bound to be higher than in ATX PSUs, 105°C caps should be used (especially in the APFC converter). Moreover, most of this unit's protection features have such high triggering points that they don't offer the desired protection levels. It's insane to measure a >40A OCP point at 3.3V in a 500W PSU. The same goes for over-power protection set in excess of 700W. Thankfully, SilverStone supports over-temperature protection. But even this is set too high for our tastes.
The pair of PCIe connectors limits this PSU's functionality. In our opinion, it would be better if SilverStone provided four connectors instead.
Moreover, the lack of an SFX-to-ATX adapter is a con in our book, even if you could argue that short modular cables mean there's no point trying to install the SX500-G in an ATX case.
Given the 85°C bulk cap, we aren't surprised by the three-year warranty. It'd actually be a challenge to offer anything longer. For that reason, it'd be great to see SilverStone upgrade the bulk cap in the next revision of this product, and nudge its warranty up to five years.
Ripple suppression on the minor rails, contrary to the +12V rail's performance, isn't that good. We won't harp on this, though, since our measurements never exceeded the 50mV limit. Plus, it's hard to find space for more filtering caps on such a small PCB.
Despite our critiques, we think the SX500-G is a good PSU that could be made much better after a handful of tweaks. Hopefully, SilverStone listens to our suggestions and implements them.
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