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PWM fan splitter confusion

HenrikTJ
By HenrikTJ
in Cooling
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Hi

 

Ive been told that only 4pin fans can have customisable fan curves, and 3pin fans have to adhere to 3v, 5v and 12v. In my build, i need fan splitters to acommodate for all my fans. I would assume that these splitters also need to be split into 2x4pins. However all i can find is splitters splitting into 1x3pin and 1x4pin. So that makes me think that only the one fan connected to the 4pin will adhere to a given fan curve and the one connected to the 3pin will go off of the 3,5,12v.

 

Am i right in thinking this?

Or will the one fan connected to the 3pin also be controlled by the custom fan curve even though its missing a pin? 

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I have 3x3-pin fans plugged into a single 3-pin system fan header through a splitter cable on my motherboard. They just treat it like one fan, and the fan curve in my BIOS seems to work even though there is no 4th pin involved anywhere.

Downside is that they get treated as one fan, but since they're identical I don't care.

i5 12600KF | Zotac RTX 4080 Gaming trinity | Team Vulcan 2x16GB DDR4 3600 | ASRock Z690M-ITX/ac | WD Black SN850x 2TB

Cooler Master NR200P v2 | ID Cooling Zoomflow 280 XT | SeaSonic Focus SGX-750 | Thermalright 2x140mm + 2x120mm aRGB

LG C2 OLED 48" 120hz | Epomaker TH80 (Gateron Yellow) | Logitech MX Master 3 | Koss Porta Pro Comm

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6 minutes ago, HenrikTJ said:

However all i can find is splitters splitting into 1x3pin and 1x4pin

there's only 3 pin on one head because 1 of the 4 pin is RPM sense, you cant read 2 fan's rpm from 1 header

so it is recommended to use the same model of fan if you'd like to use splitter like this so they will spin approximately the same speed when given the same PWM signal

 

both fans are still going to be controlled by PWM

-sigh- feeling like I'm being too negative lately

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2 minutes ago, Aereldor said:

I have 3x3-pin fans plugged into a single 3-pin system fan header through a splitter cable on my motherboard. They just treat it like one fan, and the fan curve in my BIOS seems to work even though there is no 4th pin involved anywhere.

well damn, mine dont. I tried just setting them to pwm instead of dc and set a fan curve, f10 and save. Went back to the bios after, and it was set right back to dc...

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4 minutes ago, Moonzy said:

there's only 3 pin on one head because 1 of the pin is RPM sense, you cant read 2 fan's rpm from 1 header

so it is recommended to use the same model of fan if you'd like to use splitter like this so they will spin approximately the same speed when given the same PWM signal

 

both fans are still going to be controlled by PWM

oh alright! thank you!! then all thats left is to buy the pwm fans i guess hhh

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1 minute ago, HenrikTJ said:

oh alright! thank you!! then all thats left is to buy the pwm fans i guess hhh

also you can control 3 pin fan with fan curves as well, with DC control

the voltages arent locked to 5v and 12v, i believe it can vary in small steps between these two voltages

because i can control my 3 pin fans as smoothly as my 4 pin fans

-sigh- feeling like I'm being too negative lately

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you can control dc fans smoothly but they usually cant go below 50-60% speed. which isnt really an issue with good fans but with cheaper ones they may be a little loud at that speed. pwm is usually just a few bucks more, might as well get em

topics i need help on:

Spoiler

 

 

my "oops i bought intel right before zen 3 releases" build

CPU: Ryzen 5 3600 (placeholder)

GPU: Gigabyte 980ti Xtreme (also placeholder), deshroud w/ generic 1200rpm 120mm fans x2, stock bios 130% power, no voltage offset: +70 core +400 mem 

Memory: 2x16gb GSkill Trident Z RGB 3600C16, 14-15-30-288@1.45v

Motherboard: Asus ROG Strix X570-E Gaming

Cooler: Noctua NH-D15S w/ white chromax bling
OS Drive: Samsung PM981 1tb (OEM 970 Evo)

Storage Drive: XPG SX8200 Pro 2tb

Backup Storage: Seagate Barracuda Compute 4TB

PSU: Seasonic Prime Ultra Titanium 750W w/ black/white Cablemod extensions
Case: Fractal Design Meshify C Dark (to be replaced with a good case shortly)

basically everything was bought used off of reddit or here, only new component was the case. absolutely nutty deals for some of these parts, ill have to tally it all up once it's "done" :D 

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On 8/6/2020 at 8:28 AM, HenrikTJ said:

well damn, mine dont. I tried just setting them to pwm instead of dc and set a fan curve, f10 and save. Went back to the bios after, and it was set right back to dc...

What mobo?

^^^^ That's my post ^^^^
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On 8/7/2020 at 4:23 PM, LogicalDrm said:

What mobo?

asus rog strix b450-I

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43 minutes ago, HenrikTJ said:

asus rog strix b450-I

Latest BIOS? Asus is generally the best when it comes to fan controls.

^^^^ That's my post ^^^^
<-- This is me --- That's your scrollbar -->
vvvv Who's there? vvvv

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21 minutes ago, LogicalDrm said:

Latest BIOS? Asus is generally the best when it comes to fan controls.

im running v3004. But there is a newer version available (v3103)

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