I installed mine with a 240mm aio cooler using the 8 long screws and 4 plastic locks that came with the cooler. If installing only 3 fans without an aio cooler you can try installing it from the inside of the case using the screws that came with the fan.
I bought the masterliquid ml240r aio cooler, added another fan (mf120l) connected it to the led controller but it wont change light effects. It just stays on the light blue color. The ml240r fans' led connectors are 3 pin while the mf120l is 4 pin. Or should i buy the mf120r? But my question before buying is, is the mf120r led connector 3 pin or 4 pin? If its 3 pin i guess it will work with the led controller included in the box.