Is it bad to tighten a screw too tight?

I mounted my motherboard but I think I tightened one of the screws a little more than necessary. I wasn't using an electrical screwdriver. Just by hand. I was going to untighten it but I have to push down pretty hard to get a grip in the screw and thus the motherboard slightly bends. I don't want to bend my motherboard T_T; I don't know how far is too far with mobo's so please enlighten me. Thank you for your time.

This guy acts like your the only person to ever ever ask inthe wrong section..sheez. Anyways, YES it is always bad to overtighten a screw. By definition. But if it is tight, and you dont need to remove the board, then no harm no foul. As long as you didnt crush the board your OK.

I slight bend of the motherboard wont kill it. Im curious as to why your mount point is bending though? Do you not have a standoff under the board to the tray?