Annoying PSU fan

[user587]

My first post, long time reader. Thanks to SPCR for all the great in depth articles. Unfortunately my first post is a request for help, but if I have something useful to share in the future I shall do so!

I've recently silenced several components of my PC, which has unveiled underlying sounds I hadn't noticed for the past 5 years underneath my old case/CPU fans. The component in question is my PSU (a Seasonic S12D 850w), which has a very annoying inconsistent fan. I'd never noticed it before. Its not particularly loud, but it ramps up and down every few seconds unlike the smooth consistency of a case fan. Perhaps a variation of +/-10%. Over any 5 second period it will never be consistent. It sounds like a really distant lawn mower and how they ramp up and down, but it's just a smooth sound of air.

I was wondering if anyone else has experienced this? For reasons I won't go into, I have two of these PSUs and it happens with both. On an unrelated note, one has much more coil whine than the other (the other has almost none).

Am I better off adding fans with a smooth consistent texture, or should I replace the PSU with something semi-passive like a Seasonic Platinum 1000w XP3. I could replace the fan, but it's still under warranty so that seems silly; plus its more of a controller issue than a fan noise
If I did manage to silence it, I'm pretty sure the next loudest parts in my system won't bother me as much as this one does. One last mod!

Thanks for anyone that can contribute!

[CA_Steve]

Welcome to SPCR.

Seasonic's fan controllers are temperature based...with an expected ambient temperature, the thermal rise is proportional to load power and the fan controller spins up the fan speed accordingly. The ramp is shallow at loads <50% and pretty steep afterward. So, a small rise/fall in PSU temp/load can precipitate a noticable change in fan rpm.

Without knowing anything else about your system build..if both PSUs act the same way, it leads me to believe you are either:
- operating at loads >50% of the rated power, or
- the fan controller senses enough temp rise to think the PSU is operating at >50% load (operating in a high ambient temp environment, poor PC ventilation, etc.

What's your system build? You can certainly go in and swap out the fan for a slower one...but it'd be useful to know more about the environment.

[user587]

Sure, thanks for the assist.

SETUP:
Case: CM Trooper (slight modding, side vents closed off, top vent partially closed, fan controller not in use)
PSU: SeaSonic S12D 850w
Motherboard: Gigabyte GA-Z87X-D3H
CPU: Intel i7 4770 (stock)
RAM: 8GB (2x4GB) Kingston ValueRAM
HDD: SSD SanDisk Extreme 240GB
HDD: HDD 3x Western Digital Green
GPU: Gigabyte 7970 Windforce OC
CPU Cooler: Hyper 212 EVO with Push/Pull (1300rpm Scythe PWM fans x2) (400-600rpm at idle, near to max while gaming)
Case Coolers: 3x 900rpm Scythe KamaFlow2 (One exhaust, two intake) (connected to motherboard) (400rpm at idle, near max while gaming)

TEMPS:
Ambient temp of about 18-21° on average at the moment.
HDD temps 27-29°.
CPU temp 30-35° idle, 45-55° load, 50-60° gaming (GPU contributes).
GPU temps 35° idle, 70° load (custom fan curve to reduce noise, Gigabyte curve too aggressive).

I've temporarily disabled all fans (CPU, case and GPU) and the noise must be coming from the PSU. I've done some PSU calculating and it would seem that I would use about 150w when idling, so I can't imagine the PSU being overloaded. At the moment I'm mostly idling, and the air flowing from the back of the PSU is only slightly above ambient. I know when gaming it can get quite warm, but not actually hot. I think I've probably just made my PC too silent, as the PSU never bothered me the past 5 years! It's just that the PSU isn't a consistent sound, so it keeps catching my attention even though I try to ignore it. I'd be willing to get a SeaSonic 1000w Platinum as I hear that is silent up to 300w, when my 7970 would kick in with it's loud but smoothly textured fan noise. But I'd be spewin' if I bought a PSU like that and had the same problem.

[CA_Steve]

Take a look at the SPCR review of the modular version of your PSU. It should have the same fan profile as yours. The reviewed PSU's fan was run at 3V (770rpm) until the load hit 400W and then it jumped to 4.7V (1300rpm).

Your idle power should be closer to 60W, stress load in the 430-440W range, and heavy gaming load in the 370W range. If the PSU fan is ramping up/down at idle...that's a little wacky. I'd love to know what your PSU fan speed is...

Do you feel comfortable mucking around the PSU? You could add a diode in series on the 12V line to the fan for a ~0.6V drop. If your fan is audible at 3V/770 RPM, dropping it to 2.4V will lower the speed to 470 rpm-ish.

Or, you could try replacing the 38mm wide fan that's in there with the 25mm wide Scythe Kama Flow 2 SP1225FDB12H, 1900rpm top speed, 2.8V starting voltage. At 5V, it's only 870 rpm compared to the San Ace's 1370 rpm.

[quest_for_silence]

should I replace the PSU with something semi-passive like a Seasonic Platinum 1000w XP3.

Personally I would avoid that unit, IMO it's the worst, high-priced Seasonic ever, noise-wise (sticking with a Seasonic platform, either a Snow Silent or an EVGA 1050GS would be a lot better option, IMVHO).

[user587]

Yes after further research I'm a bit puzzled with the price tag of the Seasonic 1000 Platinum. The EVGA P2 1000w is blazing the reviews though, and its far and away the cheapest here in Australia. Should I just buy one of these (with its semi-passive operation) and be done with my noise issue? I'm just a bit hesitant about EVGA products (having never owned one) and also those red PCI cables are hideous!

[quest_for_silence]

Should I just buy one of these (with its semi-passive operation) and be done with my noise issue? I'm just a bit hesitant about EVGA products (having never owned one) and also those red PCI cables are hideous!

As far as I know any SPCR forumer who bought those Super Flower-based EVGAs is perfectly satisfied: just I don't understand why you should buy a 1kW PSU when, with your quoted hardware, even an EVGA G2 750W is way more than enough in any respect, even noise-wise.

Should you buy a new PSU? IMO it's better you try at first a fan swap: replacing that high speed ball bearing fan is a noticeable improvement.

[user587]

Should you buy a new PSU? IMO it's better you try at first a fan swap: replacing that high speed ball bearing fan is a noticeable improvement.

I think this is actually very wise . Will report back how I go! Thanks

[quest_for_silence]

I think this is actually very wise . Will report back how I go! Thanks

That's about what CA_Steve suggested you yesterday: I hope it work!

[CA_Steve]

I get no love.

[user587]

Much love! I do appreciate the help, I was just slow to come around to the idea

So I've got some new fans coming in, and I was thinking of moving some case fans around. I've come to ask if its OK to unscrew and rescrew fans like the Scythe KamaFlow? I just remember when I got mine, they weren't threaded particularly well (or at all). This let them screw in quite firmly, but I'm worried if I unscrew it and move it somewhere else, it will be loose and essentially be useless. Hope that makes sense! Thanks

[quest_for_silence]

I've come to ask if its OK to unscrew and rescrew fans like the Scythe KamaFlow? I just remember when I got mine, they weren't threaded particularly well (or at all).

If I understood what you mean, please note that usually fans are not threaded at all, but you make the thread when you screw in them the very first time.

This let them screw in quite firmly, but I'm worried if I unscrew it and move it somewhere else, it will be loose and essentially be useless.

Usually you can unscrew and re-screw the fans many times before loosening the thread, just be gentle when screw them again, in order to not ruin the originally made thread: I think you will find it's much more easier than the first time (now there's a thread), and you can still tighten them up firmly, just taking enough care while.

However, noise wise it's better to use some silicone soft mounts rather than screws (even if often it's an hassle).