That's a 5V Gen 2 ARGB connector. In the motherboard manual they will probably be labelled as 'ADD GEN2_1 or ADD GEN2_2' etc. What's on the other end of that cable? Usually they are used for lighting strips where each LED can be individually controlled.
So maybe you have some case lighting? Or perhaps it is going to a lighting hub?
Z690 Hero, 12900K, BIOS 4001, MEI 2433.6.3.0, ME Firmware 16.1.35.2557, 7000X Case, RM1000x PSU, ASUS TUF OC 3090TI, 2 x 16GB Corsair RAM @ 5200MHz, Windows 11 Pro 23H2, Corsair H150i Elite AIO, 4x Corsair RGB fans, 3x M.2 NVME drives, 2x SATA SSDs, 2x SATA HDs.
