I plugged in an 8 pin cable to my psu, conmected it into the 8 to 12 pin adapter the card came with, put the card in, and plugged it in. Didn’t remove any cables or anything of that sort.Still curious why adding gpu raised CPU temps, even at idle. It shouldn't make any difference on desktop, not like its stressing.
page 3-18 of bios manual shows pump settings, I wouldn't think they change just from installing GPU though - https://dlcdnets.asus.com/pub/ASUS/mb/SocketAM4/ROG_STRIX_B450_F_GAMING/E14401_ROG_STRIX_B450-F_GAMING_UM_WEB.pdf
I assume the AIO plugged into CPU_OPT on motherboard. although it could be using AIO_PUMP connection near rear fan connector, or both...
need to work out why mb thinks the CPU overheating at boot.
Did you touch the cables at all attaching gpu?