What's the screw on the left used for? Can I use it to screw in my motherboard?

[suzukioda432]

Sorry, really dumb question, but I was wondering what the screw on the left is used for. It bought the corsair 570x and these screws came with the kit. I'm assuming I use the black one to screw in the motherboard, but could I also use the metal one?

 

[suzukioda432]

Nevermind I see they're fan screws.

 

[Alabalcho]

It is for attaching (mechanical) hard drives thru rubber grommets to reduce vibrations. Fan screws have more "wood screws" groves.