lol Freez, unstable computer is still a working one... Mohit, if you incorrectly flash your BIOS, or flash it with a wrong BIOS, you can make your computer not work all together! Follow your computer or motherboard manufacturer's instructions on how to upgrade it. Make sure you use the correct BIOS, and also make sure the power does not cut out in the middle of the flashing process
BIOS is an operating system that provides an IO interface between the hardware, at the lowest level, and the software, generally the kernel of an OS. Though not all systems use a BIOS, for example some use EFI or UEFI, and also OpenBoot. But your general x86 or 64 system will use the Basic Input Output System, it's sort of a standard now...