Reddit reviews 4 Pins black rgb LED Splitter Cable LED Strip Connector 8 Way Splitter Y Splitter for One to Eight RGB 5050 3528 LED Light Strips with,1m rgb wire，10x male to male 4pin plugs
We found 3 Reddit comments about 4 Pins black rgb LED Splitter Cable LED Strip Connector 8 Way Splitter Y Splitter for One to Eight RGB 5050 3528 LED Light Strips with,1m rgb wire，10x male to male 4pin plugs. Here are the top ones, ranked by their Reddit score.
1 to 8female connection cable rgb splitters For - 5050/3528 RGB LED Extension Cable is designed for 10mm width LED strips1 end to connect with LED RGB controller, the other ends for 8 Reel LED RGB stripsThis DC Power Adapter Cable splits 1 power signal into 8, enables you to connect 8 color changing RGB LED strips to a single controllerPower supply with sufficient amperage for 8 strips is requiredPackage Content: 1x RGB LED Strip Splitter Cable,1x 1m LED extension cord，9x male 4pin plugs (electroplated copper on the 4 pins, perfect conductivity)
Just remember to pull out the 3rd pin.
https://www.amazon.com/gp/product/B075FKL6C1/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1
There are some splitters on amazon
4 Pins black rgb LED Splitter Cable LED Strip Connector 8 Way Splitter Y Splitter for One to Eight RGB 5050 3528 LED Light Strips with,1m rgb wire，10x male to male 4pin plugs
https://www.amazon.com/dp/B075FKL6C1/ref=cm_sw_r_cp_tai_HHkzCbTTTX5QP
Not really there's a "second" cable that deals with RGB only, not the power to the fan.
they are the round pinned cable here: https://www.amazon.com/dp/B075FKL6C1/
the arrow on the cable points to PIN 1 on the motherboard.
On the motherboard they are the white connectors if you look at the 1st picture here: https://www.amazon.com/dp/B07FVYKFXF
It's Labeled RGB Header1, (Bottom left corner) and it looks like you only have the one connection point, so you'll need a splitter to extend to each fan that has it.
12V G R B and next to it is ADDR_LED1
So your motherboard can have addressable RGB and Synchronized RGB fans.