Seasonic Focus GX-750 V4 ATX v3.1 PSU Review

Average Noise

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avg_noise_230V

Similar to the 850W model, 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

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CL_Fan_Speed

The semi-passive operation is between 50W and 67W on the minor rails, with the load on the 12V rail up to 150W. 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

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CL_Fan_Speed

The fan’s semi-passive mode lasts a bit longer at 230V.