Does any one know what these pins do on skytech gaming fans

I have a skytech gaming prebuilt pc (don't ask why prebuilt, it was out of my control). I find the fans extremely loud and annoying.

I'm trying to figure out what each of the pins do so I can connect it to the case fan pins on the motherboard instead of wherever the prebuilt connected it. I tried searching online but I couldn't find anything about what function each pin serves. I also had a multimeter and battery and I figured out that the rightmost pin is positive and the second rightmost pin is ground, but I have no idea what the other 3 pins do. The center pin I measured at 5 volts, but when I connected the fan and measured again, there was no potential difference.

Does anyone knows any information about this 5 pin connector or knows where I can find documentation/specification?

Also if there are any other ways to make the case fans not run at 100% power all the time, please let me know.