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Why no lower than 40% PSU fan?


Drumcode
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I have a RM1000i and it's annoying that I can't run the fan lower than 40%.

 

One of the reasons I want to run the fan at all is so that the PSU doesn't heat up the rest of the case. 20-30% would be optimal I think for cooling/noise ratio.

 

I got so tired of the fan noise so opened it up and tried to change the fan out to a Noctua (sorry Corsair). No success though because the holes are spaced 120mm on the Corsair PSU fan as opposed to 125mm on any standard 140mm fan.

 

Someone said that the PSU team didn't want a lower curve but I'm not buying that. It doesn't make sense to me at all that I cannot choose anything in between default (0 RPM) or 40% fan (760 RPM).

 

Will this issue get addressed for future firmware/software updates?

 

If not I will just drill the holes bigger so I can fit another fan in the PSU. It will look like **** probably.

Edited by Drumcode
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It's always preferable to run the PSU half passive. if the fan runs constantly at slow speed, yea it would run cooler but you'd also have to change it sooner because bearings will wear off. Dust build up will also cause more issues even with filters.

All in all there's more drawbacks to running a PSU fan constantly versus leaving it half passive or totally passive if the system load allows.

If they did what you suggest, i would complain because my PSU has been running passive since i bought it..

 

Now it's pretty tough to have a 1kw PSU heat up enough to trigger the fan, but i don't know your build. You may use some case trickery to get air flow through it without having its fan spin, like running your case in positive pressure and having case air escape through the PSU (like installing it with fan up in a traditional case). In dual chamber cases, fans installed in the PSU chamber can create enough airflow to cool it too.

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The bearings on modern pc fans have severeral years of estimated life span when running them on 100% speed. That is because of balance, bearing technology, materials etc is so good now (Now I'm talking the top tier fans, not the budget ones like probably mounted in the Corsair PSU). Running them on 30% essentially gives them eternal life so that shouldn't be an issue (I'm pretty sure of this, I'm a mechanical engineer and this is kind of what I do for work).

 

I have a watercooled system with several (Noctua NF-A14) fans that keeps everything really cool but with the PSU fan at 0 RPM the PSU temps rise above 40C and it also heats up the rest of the otherwise so nicely cooled system. The PSU is mounted so it draws air in from underneath and vents out in the rear like any other PC but without airflow through it, it just convects the heat inside the case instead of vents it out in the back. I have a silent mode and a gaming mode in ICUE so I can quickly shift on my K70 RGB keyboard with colors indicating which mode etc.. (You know all that fun stuff probably). So in silent mode I have the radiator fans running around 500RPM, with a little bit of delta in between them to avoid resonance problems. The PSU fan at default mode (0 RPM). This makes the system dead silent and here is where the quality of Noctua really shines. I have very sensitive ears and these are the only fans I've ever came across that have absolutely zero mechanical or electrical noise on low RPMs. I still haven't tested Corsairs top quality fans yet, do you think I should do that? Maybe it would look nice with all that RGB stuff.. lol..

 

Then I have a gaming mode when the radiator fans spins up to around 1000 RPM and the PSU fan to 40%/760RPM. The funny thing here is that the PSU fan is still noisier than the Noctuas... Well, overall I'm pretty happy with the system but it would have been really sweet to run the PSU fan at 20-30%. Or maybe I want to much...? Or should I try to replace the PSU fan anyway? :) Or maybe I will try the thing with having it upside down and having some of the positive airflow through the case going through the PSU.... Maybe not a dumb idea except for that it would probably collect a lot more dust inside the PSU.

 

I just want a good explanation from the PSU team before I let this issue go. Crappy fan bearings? The bearings would hold up longer at 30% speed compared to 40% so I don't really see the logic here.

Edited by Drumcode
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Well one thing is sure, the included fan is really noisy. When i was using iCue, i tested the fan just to see if it was working and that thing really whines, like you could hear the ball bearings almost.

 

I'm ready to bet the reason why they don't run fans slower is pretty down to earth like :

-they may use simple DC fans that wouldn't reliably start at that speed

-Even if they are PWM, there's no need to run them slow since PSUs are fine running at 50°C all day long : zero RPM makes them last even longer than 30% speed.

 

With a higher temperature threshold for fan startup, you have more range to use the PSU passively in silence, which is good.

The downside is, when the fan has to kick in, it has to spin faster to evacuate the added heat..

 

It would be interesting to know the exact reason tho :)

 

Edit : if you let the PSU passive, what temperature does it get to? usually the fan kicks in around 50°C. What i saw with my HXi is that wether it's idle, or loaded when gaming it always stays under that

Edited by LeDoyen
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I got rid of my 2080 Ti so I cannot test right now, until I get the new 3080... Or 3090 haven't decided yet :confused: lol

 

I think the PSU got pretty hot, like 40-50C and the fan never started. If I'm not wrong the fan is set to start at 40% load, not any specific temperature. So if I'm getting the 3090 it will probably start in default mode. When gaming it's not a big issue... Except it could always be a little more quiet.

 

So yeah 50C is not a lot. Maybe no worries.. Maybe I should just let it be like it is. But I can't.... I want it perfect :laughing: Need to sleep on this!

Edited by Drumcode
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I'm ready to bet the reason why they don't run fans slower is pretty down to earth like :

-they may use simple DC fans that wouldn't reliably start at that speed

-Even if they are PWM, there's no need to run them slow since PSUs are fine running at 50°C all day long : zero RPM makes them last even longer than 30% speed.

 

The included fan is a (I would say medium quality) regular PWM controlled one (with noisy bearings) 140mm fan. Runs fine at lower RPM:s because I had it hooked up to the Commander Pro when I had it out to change the fan (but had to abort the mission because of the hole distance).

Edited by Drumcode
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oh HX, the fan starts at 50°C if i remember well. not sure on the exact temperature but it's temperature driven. pretty sure it's the same on all PSUs.

 

i did a test for your peace of mind (and my own curiosity) :p

unigine heaven + cinebench R20 in loop for half an hour on oc 2080 + 10900k with power limits removed.

500W power draw on the 12v pretty constant, temp went to a whooping 38° (the second sensor seen in HWINFO and not on iCue peaked at 53°, not sure what that one is). fan never started.

 

They are made to run like that from the factory, the warranty is 10 years with that fan curve :)

Power semiconductors start to act funny at 120 - 130°, the caps in these are rated for 105°.

so 40 or 50° is cool, don't kick your PC for that :p

 

If you really want a cool PSU under load, then you may consider getting a high wattage platinum, or a dual chamber case with the current one, simply moving the problem to another compartment of the case.

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This is no longer an issue to me since I've put a BeQuiet Silent Wings 3 fan in my RM1000i today. Figured out that the soft rubber mount allows the stretch for being mounted in the 120mm spaced holes of the PSU.

 

It's almost dead silent at 40% and the temp is hovering around 27C. So far so good... Only weird thing is the tacho is reading double speed from time to time so a speed controlled curve is out of question.

 

Edit: I see now there is no option for RPM-controlling the PSU-fan in iCUE anyway so it doesn't matter. Also I'm guessing that the built in speed control in the RMi is only controlling the PWM % with no input from the speed (only temp) so if the speed is reading wrong shouldn't matter?

Edited by Drumcode
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