Best answer as chosen by user tirsden: Leaving the BIOS set ...

at default settings generally will not harm anything although the normal potential for problems and issues of a non-destructive nature is always present (regardless of the settings).

Your motherboard should have come with a manual that provides you necessary information regarding the various settings within CMOS setup. Some settings can slow the PC and others can enhance its performance so you really should obtain and RTFM (Read The Fine Manual).