You need to consult your motherboard manual, to understand the implications of changing individual BIOS settings.
Sometimes, as a result of changes, you will find your system will not boot, and it is essential to know how to recover the system if that happens.
I am at a loss to understand how you could change BIOS settings from "safe mode".
Normally you enter the BIOS on initial boot-up by pressing the "delete" key, or whatever your screen tells you to do.
Perhaps, this is another function of XP, which I am unfamiliar with.