Cold Test Results

For the testing of PSUs, we are using high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M  40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs - 2014 Pipeline post.

The energy conversion efficiency of the SilverStone FX500 meets the 80Plus Gold certification requirements when powered from a 115 VAC outlet. But it fails to meet those requirements  when powered from a 230 VAC source, if only by a hair. The efficiency of the PSU plummets as the load decreases below 30 Watts, reaching 74% with a load of 25 Watts. In terms of efficiency, the FX500 does not seem to differ significantly from most 80Plus Gold certified ATX PSUs.

As expected due to its dimensions, the FX500 runs notably hotter than most ATX PSUs, even when compared to power supplies with outputs far greater than 500 Watts. Even though the tiny 40 mm is trying hard to keep the FX500 cool, the internal temperature of the unit surpasses 60°C. To be sure, these figures are not nearly high enough to be dangerous for the longevity of the unit but they are high enough to push the small fan to operate at very high speeds in order to cope with the thermal losses of the unit.

In terms of noise, the small 40 mm fan practically is a nightmare for anyone used to working with typical PCs. The small fan outputs 44.6 dB(A) worth of sound pressure while the PSU is running at a near-idle, and it surpasses 52 dB(A) under a maximum load. For comparison, a small hand-held vacuum cleaner outputs about 45 dB(A).

Introduction, Examining Inside & Out Hot Test Results
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  • Lucky Stripes 99 - Friday, November 13, 2020 - link

    I'm curious how the other cooling components in a SFF case would react to having a passive AC-DC PSU like that running at high loads. You might just be pushing the noise and heat issues to other parts of the case. It may be an acceptable trade-off if they can do the job more quietly, but it may not turn out as quiet as you might hope. For the price, there are better alternatives.
  • plewis00 - Thursday, November 12, 2020 - link

    Is this actually that impressive for size? How does it compare to an HP 1200W server PSU? Yes I know those are loud (at full load but manageable at low load) and 12V-only but they’re capable of 1200W sustained at 240V and Platinum-rated. So is this Silverstone that much of a feat?
  • thecoolnessrune - Thursday, November 12, 2020 - link

    Yes, I would definitely say it's still impressive. The Flex-ATX PSU is around 150mm long. Those 1U Server PSUs are over twice that, usually in the 330mm range. That leaves a lot more room more more circuity to get efficiency up in the Titanium range, and leaves a huge amount of room for heatsinking in the path of the air channel. In addition to that, the server PSU has an edge finger connector vs having to solder wires onto the PCB, further decreasing the real estate needed for functions that don't involve cooling the unit. A last point is that most of these modern server PSUs do not have the further conversion circuity for 5V and 3.3V busses. They outboard that to the Power Management Module. I'd say it's pretty impressive that they were able to cram wiring, low voltage conversion circuitry, and a ~450W power output in a 150mm chassis length. But it definitely came at a cost. An extra 50mm of length would have made a world of difference.
  • plewis00 - Thursday, November 12, 2020 - link

    Where on earth did you get the dimensions from? I just pulled one of the HP Common Slot PSUs from a Proliant in the office and it’s not that large - HP says they’re 3.81 x 8.63 x 19.05 cm which is not a lot bigger - and they can go up to 1200W. Yes they’re a bit larger and they don’t have wires but the edge connector takes up similar space to directly connected wires. They’re missing 5 and 3.3V rails but how much space do they take? A slightly larger PSU that is highly efficient and has a much higher wattage seems to be similar ballpark to me.
  • versesuvius - Thursday, November 12, 2020 - link

    Could you please read what you write at least once before publishing it? This kind of writing is becoming a trend in Anandtech (sign of the times?):

    "As a result, SilverStone one of the very few companies with true a variety of small form factor power and cooling solutions, rather than just a token device or two."
  • ElectroChem - Thursday, November 12, 2020 - link

    The previous sentence is no better.

    "It's a field that SilverStone has become so entrenched in that although other companies that produce compact PCs and related peripherals as well[sic[ , none of them as [sic[ really trying to be SilverStone's peer."

    Would it kill them to hire a proof-reader?
  • justaviking - Thursday, November 12, 2020 - link

    As long as we are on this topic... maybe it's just me, but...
    Page 1, third paragraph...
    You wrote: "making company PSUs an underserved market"
    Did you mean to say... *compact* PSUs...?
  • Ryan Smith - Friday, November 13, 2020 - link

    Thanks guys!
  • Ej24 - Thursday, November 12, 2020 - link

    Wonder if you could easily swap that fan for a 40mm x 20mm noctua? That'd probably move just as much air and be quieter. Don't have a need for such a tiny psu. But I'm sure I could dream of a need lol
  • Lucky Stripes 99 - Thursday, November 12, 2020 - link

    Just be mindful of the static pressure and air movement rating of the original fan and any replacement you purchase. You can probably shave a few db off with a Noctua versus stock, but I wouldn't expect miracles.

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