Question Thermaltake case fans

PC Tailor

Illustrious
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This should be on page 10 of your manual.
The 4 pin is for connecting the RGB switch mode to your MB. It is to sync to your MB colours I believe.
You should find some markings on the 4 pin that correspond with the 12V R G B - the 12V should have an arrow over it.

https://community.thermaltake.com/i...onnect-my-rgb-fan-controller-to-my-mainboard/

Not necessary to plug in unless you want that sync support is my understanding.