I entered your reply into ChatGPT, and this is what came up. I hope it helps!
Option 1 (Closest to what you want)
There is an adapter specifically made for 5-pin GPU fan headers to standard PWM fans.
The 5-pin Mini-PH GPU → 4-pin PWM splitter from MODDIY is basically designed for GPU deshroud mods. [MODDIY]
What it does:
Input: 5-pin mini PH (GPU header)
Output: standard 4-pin PWM fan connectors
This is normally used the opposite way (GPU controlling case fans), but electrically it’s the same wiring.
If your fans are already daisy-chained with the 5-pin female, you could:
GPU fans → 5-pin adapter → 4-pin PWM → motherboard header
Only caveat:
You might need a 4-pin female-to-female PWM extension after that.
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Option 2 (What most people actually do)
People with broken GPU fan headers usually run the fans straight to the motherboard.
Example adapters exist like:
4-pin Mini GPU → standard 4-pin PWM adapter (JST-PH 2.0 to motherboard header).
This lets you do:
GPU fan → adapter → motherboard SYS_FAN header
Then control with:
FanControl
MSI Afterburner
And tie the fan curve to GPU temperature.
People have confirmed this works when bypassing dead GPU headers.
https://www.reddit.com/r/buildapc/comments/zp8y87?utm_source=chatgpt.com
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Option 3 (Your DIY idea — easiest honestly)
Since your GPU fans are already daisy-chained 5-pin, you can just:
Buy a JST-PH 5-pin pigtail
Cut it
Wire it to a standard PWM fan connector
Example cable for harvesting the connector:
Then wire:
GPU fan wire → PWM header
Black → Ground
Yellow → +12V
Green → Tach
Blue → PWM
Leave the 5th wire unused.
This is literally how most custom GPU deshroud cables are made.
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One thing to double-check (important)
Many triple-fan GPUs wire like this:
GPU header → middle fan
middle fan → side fans
If only the middle fan spins, the issue might actually be:
broken fan splitter PCB
damaged fan cable between fans
not the GPU header
So bypassing the header might not fix the side fans.