Seasonic Focus GX-850 V4 ATX v3.1 PSU Review

Average Noise

The PSU’s average noise output is not that low for the category’s standards. The new PCB design doesn’t do much in this area.

Fan Noise & Speed Maps @ 28-32 °C – 115V

The semi-passive operation is between 50W and 68W on the minor rails, with the load on the 12V rail up to 180W. The programming of the MCU that controls the fan’s speed goes wild with the load pattern that I use in these tests. Normally, this shouldn’t be the case, but I am satisfied that I “caught” the worst-case scenario through these tests, and not the ideal one, because in real life, a PSU will be treated with a wide variety of load patterns, depending on each user’s system and utilization.

Moreover, users need to understand that most fan speed profiles also (indirectly) consider the load applied to the minor rails through the appropriate thermal sensors because the respective DC-DC converters lack the appropriate heatsinks, so they rely on active cooling to lower their operating temperatures. As their name implies, the DC-DC converters receive DC input, not AC, so the AC input voltage doesn’t affect their efficiency and thermal loads. This is why when you push them to the maximum, the fan’s speed will be regulated at the same levels whether you have 115V or 230V input, and this is why, in many modern PSUs, the 115V and 230V fan noise speed and fan speed maps are identical. There can be significant differences only when other parts of the PSU, except the DC-DC converters, get way hotter at 115V compared to 230V input. These parts are typically up to the APFC converter, where the input voltage is boosted at around 385VDC at the APFC converter’s output.

Fan Noise & Speed Maps @ 28-32 °C – 230V

The 230V fan noise profile is similar to the 115V one, except the small 35-40 dBA regions at full load are missing.

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6 thoughts on “Seasonic Focus GX-850 V4 ATX v3.1 PSU Review

    1. I can confirm the fan in GX-850 V4 is way too loud (I have the PSU here). Indeed it starts spinning at too high RPM. The fan curve is absolutely terrible. Even at 360 Watts load during gaming the PSU fan in the GX-850 V4 is by far the loudest component in my PC. I compared the GX-850 V4 ATX PSU against my Seasonic Focus SPX 2021 SPX-750 750W SFX PSU with a 92 mm fan (vs 135 mm fan inside the GX-850 V4) and the small SFX PSU is significantly more quiet, it is almost inaudible below 400 Watts load. The small SPX-750 is absolutely compatible with Silent PC bulds, while the GX-850 V4 is absolutely unacceptable for Silent PC builds. Also the fan curve for the GX-850 V4 is absolutely trash. After closing a video game and going from around 400 Watts down to 80 Watts idle- it takes the fan like 2-3 minutes to stop spinning meanwhile the 92mm fan inside the small SPX-750 SFX psu stops spinning after like 10-15 seconds when closing the game and going from high load back to idle. I suspect it is the “new Seasonic OptiSink Design” that requires much more cooling. While it might have a bigger surface area for cooling in total, it lacks actual physical mass of bigger metal cooling heatsinks. Because of that it needs constant and active cooling compared to solutions with big aluminium heatsinks. All the marketing talk seems to be a bunch of bull, Quote:

      “The eightfold increase in heat dissipation keeps the internals of the power supply cooler, eventually leading to improved product quality, long-term reliability, and more efficient operation.

      The redesigned layout of the power supply components and its improved thermal performance creates versatility and allows the power supply to be safely installed in any orientation.

      The OptiSink design is an eco-friendly solution that not only lowers the costs of material usage and production but also leads to energy savings in the long run.”

      What it really means is- it is way cheaper for Seasonic to manufacture and because of that, they make more profit with the new OptiSink design. The downside is that it needs constant active air cooling due to lack of mass from big metal heatsinks, which are way more effective at cooling.

      Needless to say I’ve returned the GX-850 V4, it’s absolutely terrible and unacceptable in terms of noise, I kid you not- the small SPX-750 is significantly more quiet. I made video comparisons as well, might upload them to YT later.

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