Configuring the Motherboard
- RTFM: This of course stands for "Read The Fine Manual". (Now, now, none of that please, this is a "G-rated" site. :^) ) Trying to configure a motherboard without having the manual around is an exercise in masochism. If you don't have the manual, find it, ask your vendor or local shop if they have a spare, or try to see if you can find jumpering information from the manufacturer or on the Internet. Assuming you do have the manual, read the section that describes the jumpers on your particular board. You will want to set or check every one of these jumpers. Also look at the picture of the board included in most decent manuals, to physically locate where the jumpers are.
- Set Processor Voltage Jumper(s): Most newer motherboards will have two voltage specifications, one for the internal (core) voltage of the CPU, and one for the external (I/O) voltage. See here for details on these voltage levels. Be sure to set the correct levels for your CPU; again, the manual may tell you what settings you need for the processors it supports. If you are using an older processor without split-rail voltage, set both settings the same (obviously).
- Set Processor Speed Jumpers: The speed of the processor is determined by two primary jumper settings: the system bus speed, and the multiplier (how many times the bus speed the CPU speed is). For example, a Pentium with MMX 200 uses a system bus speed of 66 MHz and a multiplier of 3x. Watch out for newer CPUs that use a lower multiplier which is interpreted differently by the CPU. For example, 233 MHz processors are often jumpered as 66x1.5, and the CPU interprets the 1.5x as 3.5x internally. Again, consult your manual.
- Set Secondary Cache Size and Type Jumper: Some motherboards accept cache in different configurations and therefore have jumpers depending on how much cache is on the board and whether it is soldered on or inserted via a COASt module. Some boards, especially those using the Intel 430HX chipset, may have a jumper that needs to be set if you have inserted a second tag RAM chip to enable caching over 64 MB of system memory. Increasingly, newer boards are doing away with these different configurations so this jumper is becoming less common. You definitely won't find anything like this on a Pentium Pro or Pentium II motherboard, since these processors have their own integrated secondary cache.
- Check Flash BIOS Jumper: If your system has a jumper to enable the flash BIOS feature, check it to make sure that it is disabled. This should be the default.
- Check CMOS Clear Jumper: Some systems have a jumper that will let you clear the contents of the CMOS memory, something that is needed most often when a system password is set and then forgotten. Make sure that this jumper is set to the normal or default position, or you won't be able to set any BIOS settings.
- Check Battery Source Jumper: Some motherboards use a jumper to determine if the onboard battery is to power the CMOS memory, or an external battery. Again, make sure this is set to the default position (onboard battery) unless using an external.
- Check Disable Jumpers: Some motherboards have special jumpers to allow you to enable or disable parts of the motherboard at a hardware level (for example, the serial/parallel ports or the floppy disk controller). Make sure that these jumpers are set properly (normally, you won't want to disable any of these items).
- Set Memory Size Jumpers: Very rarely seen on new boards, jumpers to set the size of the system memory were common on 486-class boards. Set these if your board requires them.
- Double-Check Settings: It may seem redundant to make all the settings and then check them, but it's worth a few minutes to do this. Incorrectly-jumpered motherboards are a leading cause of system problems and can be very hard to diagnose.