Minimum Fan Speeds?

Dogway · 13 Mar 2015 at 20:33

I'm thinking on running fan speeds at their minimum when PC is idling. I wonder if this can be harmful for the fans (like not designed for such low speeds).

In SpeedFan I can configure speeds lower than 60%, but RPM fluctuates a lot, sometimes reporting 0RPM when they are still working, I would probably want to set them up to 50 or 40%, and only raise when GPU is getting hot. I own an Asus Gryphon Z87, a NF-P12 and a Bitfenix Spectre 230mm.

As a side note, I read this here. "One downside to SpeedFan (and others): the BIOS settings typically have to be "full on", which means that the fans run full tilt each time you reboot until you log in and SpeedFan starts up."

When using SpeedFan, do I have to disable BIOS fan control?

new boy · 13 Mar 2015 at 20:41

hmmm. Running 4 pin fans on 4 pins headers at very low RPM should be fine.

Running 3 pin fans at low RPM should be fine, but at very very low speeds it could shorten the life of them. 40-50% doesn't sound at all excessively low to me, I'd just try not have have them on the verge of stalling.

Running 4 pin fans off 3 pin headers and limiting them via voltage isn't the best idea, but its not like they are going to suddenly blow up on you, but its not how they are designed to work, so could shorten the life of them.

What fans are they? You could probably find some specs about what the minimum RPM the manufacturer recommends.

Speedfan wont work until windows + the speed fan program is running. It should overwrite the bios fan control, so no need to disable it. Also, its going to be insanely loud when turning on if you disabled the bios' fan control, which would annoy the hell out of me.

Dogway · 13 Mar 2015 at 20:48

Yeah, that's what I thought about disabling BIOS, I just read that line on another thread and wondered... in any case CPU is always very cool very rarely would go over 45ºC.

My Noctua fan is NF-P12 PWM, so I guess 4 pin over a 3 pin header on board. The Bitfenix Spectre must be a 3 pin.

For the noctua it says: Min. Rotational Speed (PWM, +/-20%) --> 300 RPM
but I'm running it in a 3 pin header so, does it still makes sense?

Also do you know how to reduce knot point in speedfan? there are too many (like 20 or 30) to configure easily...

new boy · 13 Mar 2015 at 20:54

Dogway said:
Yeah, that's what I thought about disabling BIOS, I just read that line on another thread and wondered... in any case CPU is always very cool very rarely would go over 45ºC.

My Noctua fan is NF-P12 PWM, so I guess 4 pin over a 3 pin header on board. The Bitfenix Spectre must be a 3 pin.

For the noctua it says: Min. Rotational Speed (PWM, +/-20%) --> 300 RPM
but I'm running it in a 3 pin header so, does it still makes sense?

Also do you know how to reduce knot point in speedfan? there are too many (like 20 or 30) to configure easily...

If your running it off a 3 pin header then noctua's ratings don't really apply. 4 pin PWN will be kinder on the fan than a similar speed achived via 3 pin voltage control.

I wouldn't worry too much about it though TBH. I mean, what's the point of having a nice fan if you can run it the way you want?

I've never actually used speedfan, so I cant offer you any advice there. I used ASUS fan xpert 2, which does similar things, and was happyish with that for a while.

Dogway · 13 Mar 2015 at 21:00

I just confirmed and it is as I said.

The single PWM header on board is used for the CPU fan (the rad fan), since there are not more headers I need to run the others in 3 pin connectors.
So you would say it's safe to run the noctua at 50 or 40% even it's on a 3 pin header...

Thanks for help.

new boy · 13 Mar 2015 at 21:01

I'd say go for it.

Tealc · 13 Mar 2015 at 22:29

Why would running a 3 pin fan at low speed shorten its life? As it is a motor that has moving parts faster speed will kill it rather than a weak magnetic field.

Pwm fans as pointed out don't respond well to low voltage but it is more about the electronics in this case and what tends to happen it the fan will suddenly kick from zero to 600rpm once the threshold is reached. A 3 pin fan will run stupidly slow and do it for years.

Dogway · 13 Mar 2015 at 22:40

Thank you Tealc!

I bought the PWM thinking in the long run, since I learned I could plug it in both 3 and 4 headers... I guess it wasn't without compromises... I will probably buy a 3 pin fan then.

I was having a look at voltages in speedfan, to check if anything moved at all when I zeroed the fan, but nothing changed... do you think speedfan reduces voltage or does something else... just wondering.

Tealc · 13 Mar 2015 at 22:58

I'm not sure. I think it interfaces with whatever your motherboard is set to. It certainly reported whatever my GPU fan pwm was accurately and modified it well enough.