Worth looking at higher power zero RPM/semi passive PSUs?

[JerryTheC]

I'm in the early stages of planning a new build to replace my (very!) old PC.

I'd like to keep the noise level down; one possible part of that might be to go for a higher power PSU with a zero RPM mode,
on the basis that if I aim for something where the normal load is below the level where the fan kicks in, in theory that ought
to give a silent PSU.

Has anyone tried this? does it actually work in practice, or do you just get a delay before things heat up and the fan starts?

[kalniel]

I don't have one, but most high end PSUs have a zero-fan mode now - no need to over spec as it's based on temperature, not % load, and you might end up creating more temp running a high spec PSU at lower % load than a low-spec running in it's most efficient load.

[JerryTheC]

I don't have one, but most high end PSUs have a zero-fan mode now - no need to over spec as it's based on temperature, not % load, and you might end up creating more temp running a high spec PSU at lower % load than a low-spec running in it's most efficient load.

Looking at some of the Corsair PSUs on scan's website, which have both efficiency and fan noise graphs, it looks as though peak efficiency is at around 40-60% load, and shows the fan kicking in at around 40% (and ramping up a lot over around 60%). I presume that's based on the temperature it reaches at a steady load, so aiming for a typical load a bit under the 40% mark would hopefully both be in the more efficient range (reducing waste heat) and stand a reasonable chance of keeping the fan off. I'm not sure whether having it jump from silent while it heats up to max fan trying to cool things down when it gets too hot would be worse than a steady state quiet fan...

[NonLinearLines]

If you check out any of Tomshardware/KitGuru/AnandTech reviews for specific PSUs, their reviews have graphs that show PSU noise level based on load. They're incredibly helpful for figuring out exactly what you want. Then it's just finding a PSU with a low enough noise level at the wattage you'll be using.

[Sleeperz]

Even if your system load is below the threshold for silent operation, the fans can still kick in if components inside the PSU are too hot. My previous RM850x would ramp up its fan even on system idle, due to the poor airflow it received and perhaps dust buildup

[Xlucine]

I've had bad luck with seasonic "semi-passive" PSUs - 3 in a row that had to spin the fan at ~50% duty cycle when drawing ~50W (10% of the rated capacity) after a few hours of use. Luckily Scan accepted a claimed semi-passive PSU that was not semi-passive as a faulty good when I returned it (and the two other identical ones we tried). My current fractal design one does the semi-passive thing like it should

[wazzickle]

What components are you looking to run - what wattage do you think you'll need? I've had two entirely passive PSUs that have served me very well, though in entirely silent builds i.e. no GPU and so quite low wattage.

In general people seem to go overboard in terms of power for PSUs, the only online calculator tool I'd use would be pcpartpicker.com

[CAT-THE-FIFTH]

My Corsair SF450 and SF600 seem to run passively even at relatively high loads. I remember testing my SF450 and even at 200W~250W from the wall when driving a Xeon E3 1230 V2 and a GTX1080,the fan rarely spun up.

[DanceswithUnix]

My Corsair SF450 and SF600 seem to run passively even at relatively high loads. I remember testing my SF450 and even at 200W~250W from the wall when driving a Xeon E3 1230 V2 and a GTX1080,the fan rarely spun up.

I presume you have a case fan drawing some air through it?

[CAT-THE-FIFTH]

I presume you have a case fan drawing some air through it?

I initially tested the SF450 outside the case,and it barely ran the fan. Even in my case after using it for over 4 years(original case had a single 120mm intake and a single 120mm exhaust),the fan must not have spun that much,as there is virtually no dust on the fan blades or in the unit. I am now running the SF450 in a 5 litre Velka 5 case,which has no fans,but has mesh sides. I will try and see if the fan actually spins up when the system is under heavier load. However,its only a TDP capped Core i5 10400 and a GTX960 4GB. So far I have not heard it spin up.

[Jonj1611]

Not sure about other PSU's but on my EVGA power supply the fan won't come on until the PSU hits 55c