front intake

Im using a fan hub and an 850w psu. Recently, I changed my top exhaust fans with non rgb fan to single color led fan. When I turn on my pc, one of the front intake fans need to be hand started and it doesn't seem dirty. What could be the solution for that?

Hello there, TL;DR: I have the NZXT S340 non-Elite. If I place two Corsair ML140 Pro LED White fans in the back, do I need any front intake fans? Will the negative pressure suck in extra dust? Right now I have an NZXT S340 (non-Elite) with two stock fans in the back, and two Corsair AF120...

These fans have two cables attached. One is the 4-pin cable for power, and this was connected with a splitter. Both fans operate normally. Another connector is a 4 pin connector with a blocked 3rd pin. These are what Fractal calls "chained connectors."...