How to Reduce Fan Voltage?

naylord
Posts: 46
Joined: Sat May 21, 2022 11:55 pm
Has thanked: 12 times
Been thanked: 3 times

How to Reduce Fan Voltage?

Unread post by naylord »

I have a stock fan, and I'm pretty sure it runs at 5v by default. I see a lot of people mentioning "running fans at 3.3v" to reduce fan speed since with a decent heat sync you're probably fine on cooling. I thought it might be a nice way of reducing noise without needing to buck up and get a Noctua. How is this done?

User avatar
kathleen
Top Contributor
Posts: 414
Joined: Fri Jun 26, 2020 4:23 am
Location: Belgium
Has thanked: 226 times
Been thanked: 134 times

Re: How to Reduce Fan Voltage?

Unread post by kathleen »

To my recollection, the IO board has a jumper to set the fan voltage to 5.0 volts or 3.3 volts.
My set has already a switch to select one or the other speed, I guess this switch is connected in lieu and place of the jumper.
Pay attention that maybe not all 5.0 volts fans are capable to start to turn with 3.3 volts.

Edit: Found the confirmation of this at least for the IO v6.1 from ultimate mister (the one I have :-))
https://ultimatemister.com/product/i-o-board-6/

Look at this PDF : https://github.com/MiSTer-devel/Hardwar ... rd_6.1.pdf
At the left side, almost at the middle height, there is the FanSW to select the fan voltage (could be a jumper in case the switch is not installed I guess or depending of the revision of your IO board)

かすりん

User avatar
LamerDeluxe
Top Contributor
Posts: 1179
Joined: Sun May 24, 2020 10:25 pm
Has thanked: 821 times
Been thanked: 264 times

Re: How to Reduce Fan Voltage?

Unread post by LamerDeluxe »

I set my 5 volt RGB fan to 3.3 volt this way (6.1 board) and even the RGB effect still works fine. The fan is a whole lot more quiet this way and still cools sufficiently.

naylord
Posts: 46
Joined: Sat May 21, 2022 11:55 pm
Has thanked: 12 times
Been thanked: 3 times

Re: How to Reduce Fan Voltage?

Unread post by naylord »

kathleen wrote: Tue Mar 14, 2023 5:46 am

To my recollection, the IO board has a jumper to set the fan voltage to 5.0 volts or 3.3 volts.
My set has already a switch to select one or the other speed, I guess this switch is connected in lieu and place of the jumper.
Pay attention that maybe not all 5.0 volts fans are capable to start to turn with 3.3 volts.

Edit: Found the confirmation of this at least for the IO v6.1 from ultimate mister (the one I have :-))
https://ultimatemister.com/product/i-o-board-6/

Look at this PDF : https://github.com/MiSTer-devel/Hardwar ... rd_6.1.pdf
At the left side, almost at the middle height, there is the FanSW to select the fan voltage (could be a jumper in case the switch is not installed I guess or depending of the revision of your IO board)

Right, I have the exact same one as well. So is there a switch on the bottom side of the board? I just popped off the top of my case to take a look but based on the diagram JP3V/JP5V should be on the bottom. I see the product page even mentions there's a selector for 5/3.3 volts on the fan. Is it just a small little switch on that part of the diagram? I just want to make sure I know what to look for before I dissassemble my MiSTer.

User avatar
LamerDeluxe
Top Contributor
Posts: 1179
Joined: Sun May 24, 2020 10:25 pm
Has thanked: 821 times
Been thanked: 264 times

Re: How to Reduce Fan Voltage?

Unread post by LamerDeluxe »

naylord wrote: Fri Mar 17, 2023 3:20 am
kathleen wrote: Tue Mar 14, 2023 5:46 am

To my recollection, the IO board has a jumper to set the fan voltage to 5.0 volts or 3.3 volts.
My set has already a switch to select one or the other speed, I guess this switch is connected in lieu and place of the jumper.
Pay attention that maybe not all 5.0 volts fans are capable to start to turn with 3.3 volts.

Edit: Found the confirmation of this at least for the IO v6.1 from ultimate mister (the one I have :-))
https://ultimatemister.com/product/i-o-board-6/

Look at this PDF : https://github.com/MiSTer-devel/Hardwar ... rd_6.1.pdf
At the left side, almost at the middle height, there is the FanSW to select the fan voltage (could be a jumper in case the switch is not installed I guess or depending of the revision of your IO board)

Right, I have the exact same one as well. So is there a switch on the bottom side of the board? I just popped off the top of my case to take a look but based on the diagram JP3V/JP5V should be on the bottom. I see the product page even mentions there's a selector for 5/3.3 volts on the fan. Is it just a small little switch on that part of the diagram? I just want to make sure I know what to look for before I dissassemble my MiSTer.

Mine doesn't have a switch, so it is just a matter of shifting the jumper over one position. It is located at the top side of the board, next to the fan connector.

naylord
Posts: 46
Joined: Sat May 21, 2022 11:55 pm
Has thanked: 12 times
Been thanked: 3 times

Re: How to Reduce Fan Voltage?

Unread post by naylord »

Ah yeah, found the jumper. I actually learned what a jumper is doing this just now. It slid off and went to the other pegs easily. I was startled when I botted it up though and it sounded like a jet engine! It turns out, the jumper came configured on the 3V and I just moved it to the 5V! Oh well, I moved it back but now I guess if I want it to be silent I'll need to buy a premium fan.

Thanks for the help

Stinky
Posts: 84
Joined: Mon Nov 15, 2021 9:05 pm
Has thanked: 47 times
Been thanked: 9 times

Re: How to Reduce Fan Voltage?

Unread post by Stinky »

I have a standard hamburger with heatsink, works fine without a fan give it a try.

User avatar
ADV7842
Posts: 8
Joined: Sat Jan 23, 2021 11:48 am
Has thanked: 3 times

Re: How to Reduce Fan Voltage?

Unread post by ADV7842 »

I want to run my noctua fan also at 3.3V that should work right? My I/O Board is missing the fan header :( Stupid question but which Jumper do I need to buy? It seems there are 2 versions what are their differences?

41000598.jpg
41000598.jpg (76.99 KiB) Viewed 636 times
s-l1600.jpg
s-l1600.jpg (21.59 KiB) Viewed 636 times
Xbytez
Site Admin
Posts: 471
Joined: Wed May 20, 2020 3:36 pm
Has thanked: 215 times
Been thanked: 791 times

Re: How to Reduce Fan Voltage?

Unread post by Xbytez »

From the pictures either type will work they are just open and closed tops for the jumper/shunt, that is the only difference.

User avatar
ADV7842
Posts: 8
Joined: Sat Jan 23, 2021 11:48 am
Has thanked: 3 times

Re: How to Reduce Fan Voltage?

Unread post by ADV7842 »

Can a Noctua 5V Fan reduced to 3.3V or doesn't it turn on?

Xbytez
Site Admin
Posts: 471
Joined: Wed May 20, 2020 3:36 pm
Has thanked: 215 times
Been thanked: 791 times

Re: How to Reduce Fan Voltage?

Unread post by Xbytez »

ADV7842 wrote: Sun Mar 31, 2024 8:06 am

Can a Noctua 5V Fan reduced to 3.3V or doesn't it turn on?

Yes, the 5 Volt Noctua starts and spins fine on 3.3 Volts.

FPGA64
Top Contributor
Posts: 765
Joined: Mon Mar 01, 2021 3:10 pm
Has thanked: 44 times
Been thanked: 327 times

Re: How to Reduce Fan Voltage?

Unread post by FPGA64 »

To be honest I have never heard my Noctua at 5v. People must have better hearing than me!

Post Reply