@mcc not sure if this helps, but I believe this is the manual for that motherboard. It should have a board layout. https://dlcdnets.asus.com/pub/ASUS/mb/LGA1151/PRIME_H270M-PLUS/E12027_PRIME_H270M-PLUS_UM_WEB.pdf?model=prime_h270mplus

@mcc CHA_FAN2 stands for chassis fan 2. It's a connector for one of your fans. Most likely the rear fan or for a side panel fan if your case has one.

@mcc You can sometimes tell which cable is for the CPU power by checking if any of the 8pin cables split at the end. They are usually 2 4 pin cables stuck together. Then from there, you just have to orient it so that the clip latches onto the motherboard connector