H100i PRO RGB - can only get 1/2 radiator fans spinning, possibly a bad splitter?

Hi everyone, I just put together a mostly new PC, and immediately I could see that one of the fans on the radiator wasn't spinning at all. I checked the connections and it seemed that everything was solid, and both fans were connected. I swapped them at the splitter to see if it was just a bad fan, but after starting the system again I saw that the previously spinning fan was stopped, and the previously stopped fan was now spinning. So to me that seems like either the splitter is bad, or I have a bad connection somewhere else, or I have a psu problem? I was thinking that maybe I need to replace the power supply because it's pretty old. /edit: I think it's a Corsair CSM 750.

Attached is a snip of my icue dash. I only just got the PC running so I haven't done any stress testing or anything, but I did have the pc hard reset earlier today while I was playing final fantasy 14 (would not have thought that would push the system much). I had set a notification to turn all my lights yellow if the temps got over 70c and I didn't see that, so IDK if the reset was temps or something else.

I also circled the chassis fans in icue because it's showing 3 active fans when I only have two, which i'm a bit confused about.

I can check the connections again. I also have some extra fans i could replace to see if it somehow is a problem with the fan. I can check BIOS settings again (set cpu header to full speed / pwm).

Would really appreciate any input I can get, sorry in advance for not doing more research or looking around for similar problems but there's a lot of outdated and less relevant info out there and don't want to make it worse.

It does appear to be a bad fan wire on the H100i Pro. Contact Corsair Support through the Ticket System so they can send you a new one. In the meantime, if you have a standard PWM fan splitter lying around, you can connect both radiator fans to the working channel. There isn't much need for independent fan control.

The information iCUE reads from the motherboard isn't always interpreted correctly. It could be in how the header is wired (like a CPU/OPT shared slot) or it could be something else. Either way, figure out which one is doubled and you can drag it out of the motherboard box into its own space, then delete it. This is far more common with temperature readings, but trying to pin those down is considerably harder.

It does appear to be a bad fan wire on the H100i Pro. Contact Corsair Support through the Ticket System so they can send you a new one. In the meantime, if you have a standard PWM fan splitter lying around, you can connect both radiator fans to the working channel. There isn't much need for independent fan control.

thanks for the reply! It's a shame to return over such a minor flaw, but i will go ahead and open a ticket and see what comes of it. thanks again!

The information iCUE reads from the motherboard isn't always interpreted correctly. It could be in how the header is wired (like a CPU/OPT shared slot) or it could be something else. Either way, figure out which one is doubled and you can drag it out of the motherboard box into its own space, then delete it. This is far more common with temperature readings, but trying to pin those down is considerably harder.

I think I've actually encountered this before now that you mention it. I didn't know I could drag them out of the boxes, so if I can determine which one is incorrect I will do that. Thanks!