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Virtually all PCs built since 1996 use a flash ROM to store the BIOS. A flash ROM is a type of EEPROM chip you can erase and reprogram directly in the system without special equipment. Older EPROMs required a special ultraviolet light source and an EPROM programmer device to erase and reprogram them, whereas flash ROMs can be erased and rewritten without you even removing them from the system. On some systems, the flash ROM is not a separate chip but instead might be incorporated into the southbridge chip.
Using flash ROM enables you to load the upgrade into the flash ROM chip on the motherboard without removing and replacing the chip. Normally, these upgrades are downloaded from the manufacturer’s website. Depending on the design, some update programs require that you place the software on a bootable optical disc, whereas others configure the program to run on the next startup (before Windows loads), and still others actually run in Windows as a Windows application.
Some systems allow the flash ROM in a system to be locked (write-protected). In that case, you must disable the protection before performing an update—usually by means of a jumper or switch. Without the lock, any program that knows the correct instructions can rewrite the ROM in your system, which is not a comforting thought. Without the write-protection, virus programs could be written that overwrite or damage the ROM BIOS code in your system. The CIH virus (also called the Chernobyl virus) was one example that could overwrite the BIOS code on certain motherboards. Instead of a physical write-protect lock, some flash ROM BIOSs have a security algorithm that prevents unauthorized updates. This is the technique Intel uses on its motherboards, eliminating the need for a lock jumper or switch.
Note that motherboard manufacturers do not normally notify you when they upgrade the BIOS for a particular board. You must periodically log on to their websites to check for updates, which you can then download and install at no charge.
Before proceeding with a BIOS upgrade, you must locate and download the updated BIOS from your motherboard manufacturer. Log on to its website, and follow the menus to the BIOS updates page; then select and download the new BIOS for your motherboard.
Motherboard manufacturers may offer several ways to update the BIOS on a given motherboard, some may run directly from within Windows, and others might need to be run from bootable removable media such as optical or USB. You only need to use one, so if you have choices, in most cases you should choose the one that is the easiest to perform. Which one you choose can depend on the current state of the system. For example, if the BIOS is corrupt, you may have no other choice but to use the emergency recovery procedures shown in the next section. If the system you are updating is one you are building for the first time and does not yet have a working copy of Windows installed on the hard drive, you might want to use a method that works with other bootable media such as an optical drive or USB flash drive.
Most downloadable flash ROM upgrades fit into five main types:
- Windows executable upgrades
- BIOS Setup executable upgrades
- Automated images of bootable media
- User-created bootable media
- Emergency recovery media