Question Frankenstein gpu fan not reporting RPM to Mobo Header.

Jun 4, 2019

I currently have an MSI B450M Mortar Max Mobo. It has 3 4Pin PWM/DC mode system fan headers. I have an MSI RX 470 Armor OC which had problems with its fans not spinning. What I did is I bought a replacement set of fans but they did not work either when plugged into the gpu's fan header.

So I got myself an intel cpu heatsink and harvested its 4 wires and connector so that I can wire them to my replacement fan and connect the fans to 1 of the system fan headers of the motherboard. I made sure that I connected and soldered the wires properly and checked 4 pin pwm fan diagrams. It worked on my previous motherboard which is an old 1150 board from ASUS but when I upgraded to my new pc the MSI's board bios does not detect the fans being plugged and does not report RPM. Although I can control the fans when I adjust the fan curve on the specific header the fans are plugged into.

One thing to note though that the other fan of the gpu has only 3 wires in it which is connected to the other fan that has 4 Pin. In my understanding though, it should not affect the rpm reporting as the 3rd pin is supposedly the sense pin and the 4th is for pwm control?

Any ideas as I ran out of any logical explanation as to why this is the case?