Wow thank you. Is it as simple as pulling out the molex for the fan I want to replace and stick in a new fan with a converter?It's quite outdated at this point "molex" connector. Depending on what type of fan you want to buy you'll have to get molex-to-3pin or 4 pin adapter as it's highly unlikely you'll get fans that have a molex adapter at this point.
I just looked at the molex and it seems to be a 4 pin, I have a asus h170 pro and a NZXT phantom case. Not sure about the fans just some NZXT ones. I bought some cheap ones off Amazon that come with a molex cable with them just now. Most likely replacing the faulty fan and installing an extra one at the top of the case as wellthe molex is use for a 3 pins fans also so name and model of case same for motherboard and fans you want to had in the case .