Corsair SF850 ATX v3.1 PSU Review

Average Noise

The average noise output is below 30 dBA at 115V and below 28 dBA at 230V, where efficiency is higher. Given the small form factor and the increased power density, the noise output results are ok.

Fan Noise & Speed Maps @ 28-32 °C

[115V] The fan’s noise remains low as you don’t stress the minor rails, even if the load at 12V reaches 400W. If Corsair had kept the maximum combined power on the minor rails at 100W, the unit’s average noise output would have been notably lower. The 30 dBA mark is passed at around 565W at 12V, while with more than 630W at the same rail, the fan’s noise exceeds 35 dBA.

As you will notice from the CL_Fan_Speed graph, the fan’s passive operation doesn’t last long. On the contrary, it only lasts for a short period because, during these tests, I gradually apply full load on the minor rails, steadily increasing the load at 12V during every minor-rail load circle. This specific load pattern is the worst possible scenario for this platform, but from the moment its official power specs mention 130W max combined load on the minor rails, I must follow them. Although the fan spins between 400-600 RPM at a light and moderate 12V load and with the combined load on the minor rails remaining below 85W, its output noise is still low, below 6 dBA.