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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  • RealBeast - Thursday, November 12, 2020 - link

    Doh, this looked promising for a small custom HTPC build until I read the sound issue.
  • Lucky Stripes 99 - Thursday, November 12, 2020 - link

    If you are looking for a nearly silent PSU for a SFF HTPC, good luck finding one. Almost all of the FlexATX PSUs use little 40mm fans that struggle to move air quietly. Even the 160W unit in my Inwin Chopin case was noticeable when using it as a HTPC. So I pulled the original PSU and replaced it with a fanless 12V DC-DC ATX pico-PSU style board paired with a 220W 12V laptop brick. Since the majority of the work is being done outside of the case, the Noctua HSF atop my AMD 3400g is enough to keep the DC-DC board cool. The downside of a pico-PSU style board is that it is a tight fit near my memory modules, but since nobody makes a FlexATX sized DC-DC supply outside of some stupidly expensive ($200+) industrial models, it was the route I was stuck with.
  • rabw - Friday, November 13, 2020 - link

    If you have room for a SFX PSU, the Corsair SF750 is passive up to 300W.
  • Valantar - Friday, November 13, 2020 - link

    There are options, but you need to abandon traditional form factors. I just built a silent, semi-fanless Renoir HTPC using a MeanWell RPS-200-12C AC-12VDC PSU plus a plug-in DC-ATX board. The PSU can run on convection cooling up to ~150w, which far outstrips the needs of my 4650G.

    Still, the market for this Silverstone unit is more for the people buying SFF cases off TaoBao - there are dozens if not hundreds of designs there for FlexATX PSUs and relatively large GPUs, and until now the only real PSU option has been refurbished server units. I'm expecting a lot of these will get Noctua fan swaps in short order though.
  • DanNeely - Thursday, November 12, 2020 - link

    There's no way to move a meaningful amount of air with a 40mm fan that's not going to be loud.

    Sadly, it doesn't appear to have a low power fanless level. At least 50-100W should be doable (maybe a bit more); that's a mainstream laptop power brick, and if being inside a case means this won't have as easy passive cooling it's also several times larger than a brick.
  • MenhirMike - Friday, November 13, 2020 - link

    If you only need 50-100W, then a PicoPSU is a great option. Looks like they have models that go up to 160W, I myself have an 80W Model (only with a 60W laptop power brick though) and it does what it needs to do.
  • DanNeely - Friday, November 13, 2020 - link

    If you never need more than that much power, then yes something like this would always be the wrong choice. ~100W before the fan came on would be for an SFF system with a discrete GPU that was near silent at idle and only made noise under load.
  • Lucky Stripes 99 - Friday, November 13, 2020 - link

    There are now numerous PicoPSU clones on the market with much higher peak wattage. HDPlex has 200W models, RGeek has 250W models, and G-Unique has 450W models.
  • meacupla - Friday, November 13, 2020 - link

    You can add an 80mm fan to the side if you cut a hole into the side of it.
    Of course, it's no longer Flex ATX sized at that point, but it's still smaller than an SFX PSU.

    There are also TFX PSUs, but they tend to lag even further behind than Flex when it comes to higher power output.
  • Spunjji - Friday, November 13, 2020 - link

    If you're after something quiet and don't need high power output then FSP make a 150W fanless model, the FSP150-50FGBBB. It doesn't have a lot of connectors, though, so you'd need to plan a build accordingly.

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