Long story short I ended up with an extra fan so I decided to throw it on the other side of my Hyper 212 Evo to get a push/pull system going. My MOBO has two connections marked for a CPU fan, called CPU_FAN1 and CPU_FAN2. FAN1 has 4 pins like normal, but FAN2 only has three (which is pretty dumb, I think). My extra fan is kinda loud at full blast so I really would rather use all 4 pins. I looked and I only have one more 4 pin, but it's for a chassis fan, marked CHA_FAN1.
I know it's more than likely perfectly safe to plug the extra fan into those pins, but since it's for a chassis fan, will it accurately report my CPU temperature to the fan so that it can speed up/down accordingly? Or will it use a different temperature (such as ambient) to control the speed? I don't exactly know how that works, so I wanted to check here before trying it out.