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What's the 5 pin plug on the right for?
The fans connected to this controller have stopped lighting up all at once. They still blow and can adjust their speed. Just no light.
Can I control their light/colour from JRGB on my motherboard?
I don't have a cable for the 5 pin socket on the right.
It might be a USB interface. But you would have to figure out the pinout as I would assume they would make it not default, hell they might have just exposed the JTAG there and not fucked with a USB chip. But again you would need something that can figure that out (bus pirate or the like, but that is just more $$ then just getting a new one, or a different fan controller that works for you).