Motherboard CMOS Configuration and Setup

Author: Arielle Sampson (and one other contributor)

Do you need to set up or change your computer motherboard’s CMOS, BIOS, and chipset settings? When your computer system starts up, the BIOS boot screen appears momentarily. While this boot screen is being displayed, you can press a designated key to run the CMOS Setup program. CMOS Setup is used to configure BIOS and chipset settings ranging from those as obvious as the Date and Time to those as obscure as memory timings and bus settings.

BEAUTY IS ONLY SKIN DEEP

Some motherboards are programmed to replace the standard BIOS boot screen with a logo splash screen, which contains an image, a logo, and the current version of the software. To display the standard BIOS boot screen on such systems, press the ‘Escape’ key while the logo splash screen is visible.

To invoke CMOS Setup on most computers, press ‘F1’ (AMI), ‘Del’ (Award), or ‘F2’ (Phoenix). Some BIOS manufacturers use different keys. The key that invokes your system’s CMOS Setup nearly always appears on the BIOS boot screen. If your BIOS boot screen isn't displayed or does not show the CMOS Setup key, try pressing ‘Esc’, ‘Del’, ‘F1’, ‘F2’, ‘F10’, Ctrl-Alt-S. Alternatively, try to find your system’s user manual or other documentation to find the CMOS Setup key.

The appearance of CMOS Setup and the available options depend on the chipset, the BIOS make, and version. The appearance and options can also be altered by changes made to the BIOS and CMOS Setup programs by manufacturers. For example, two motherboards may use the same chipset and BIOS, but one may give users complete freedom to configure chipset options, and the other may allow users to access only certain settings and uses hard-wired values for other settings. Hard-wired values cannot be changed by the user.

All BIOSs have default settings that are designed to allow the system to boot and function normally. Aside from those settings, you can choose settings to configure the system and to optimize its performance according to your needs. Some BIOS settings are understandable things like time and date, power management, boot sequence, and so on. Other settings, especially those characterized as advanced settings or chipset settings, can be obscure. The brief help descriptions provided with these obscure settings are not generally helpful unless you already understand what the problem is. The primary rule here is if you don't understand what a setting is for, it’s probably safer to not change it.

Sometimes, however, accepting default settings can result in a system that performs below its potential. PC and motherboard manufacturers differ in how "aggressive" their default settings are, especially those for such things as memory timing. Manufacturers that choose slower default settings explain that they cannot predict what components a user will install, particularly with respect to speed and quality of memory. Choosing less-optimal settings allows manufacturers to ensure that the motherboard will at least work, if not optimally. PC makers who control the specific memory and other installed components sometimes default the settings to more aggressive options. These makers assume that users want the highest possible performance and include components that support those performance-oriented settings.

Look for CMOS Setup instructions in the manual that came with the computer or motherboard. If you do not have these manuals, see a web page that supports that product. Some manufacturers provide detailed explanations of general CMOS Setup and Chipset Setup options, but many cover only basic BIOS settings and ignore chipset settings entirely. If your manual only covers basic settings, the best sources of information about advanced BIOS settings are Wim's BIOS (http://www.wimsbios.com) and Phil Croucher's The BIOS Companion (http://www.electrocution.com/biosc.htm).