Inspiron 5680, adding a front fan?

As suggested, the spot on the front of the 5680 case is designed to accept a 92mm fan. I bought a Noctua NF-A9 PWM. Successfully installing it wasn’t as simple as I’d hoped (it had to be installed entirely from inside the case), but I managed:

1. Removed the two screws holding the black graphics card support cage in place and moved it out of the way.
2. Inserted the four rubber pegs into the large holes provided in the case and then slid them up and out (top 2) or down and out (bottom 2) into the smaller lock holes meant for them.
3. Threaded all four pegs into the matching holes on the fan and then pulled each peg hard to lock it in place—except the bottom left one. There’s no way to reach that peg from within the case.
4. Plugged the fan’s cable into the nearby 4-pin PWM header on the motherboard.

Notes

• Even without the last peg secured, the fan seems solid enough and doesn’t wobble.
• Although I also removed the front cover of the 5680, doing so didn’t give access to the fan holes. I also removed the 7 or so screws that secured the additional cover beneath it. But I didn’t see a way to remove it, so I just put the screws back in.
• Connecting the fan to the PWM does not cause a startup error. Like the two original fans (back and CPU), its speed is correctly controlled by the motherboard.