Davor Brdar

Hello, I just put together a new rig. My motherboard is Gigabyte Z170 Gaming 7 with i56600K cpu. As a cpu cooler i put on Nepton 240M. I connected water pump to CPU_FAN header and cooler fans with provided Y-splitter to CPU_OPT header. In BIOS I set CPU_FAN to "Full Speed" and CPU Fan (water pump) is doing ~2.600 rpm constantly. CPU_OPT is set to "Normal" so that cooler fans can increase or decrease operation depending on temperature and workload. CPU_OPT is doing ~980 rpm at idle. My problem is, ONLY one of the fans on Nepton is spinning. When I try to change fan connectors on the Y-splitter, again only one fan is spinning but now it's the other one. I tried connecting one by one fan to each of the Y-splitter connectors and only one connector of the Y-splitter is making fans spin. Also I noticed that one connector on Y-splitter has 4 wires in a 4 wire connector and the other one has 3 wires in a 4 wire connector. Is everything I wrote normal or should both cooler fans spin when I turn on power? Is it maybe a faulty Y-splitter? Did I connect the pump and the fans correctly to the motherboard? Also, if I connect fan connectors to SYS_FAN headers on motherboard (there are 3 of those) will they know when they the cpu is hot and ramp up the RPMs? Please help! Thank you!