Configuring a Mother Board Which Uses Jumpers
You need to have the manual for your board available. If you do not have the manual, log on to the manufacturer’s web site and see if you can find this info there. You can also try their tech support via phone. In some cases, too, some of the jumper settings are printed onto the surface of the motherboard. If you don’t have any of this info, you are just out of luck. Unfortunately, you must have some form of documentation available simply because motherboards have so many settings to adjust. If you’re dealing with an older board, you may need to spend some time trying to identify the manufacturer so that you can see if they do support it. You can many times use the BIOS ID numbers to identify the board online.
Motherboard manuals come in two main formats. Some are friendly for hardware buffs by listing a separate jumper or DIP switch for CPU core voltage, I/O voltage, multiplier, and system bus speed. They then tell you the settings for each of these. This format is better because of the increased control. Other manuals list the settings next to a list of commonly used CPU’s, showing the common settings for each. While this format is easier for the end user for easy setup, it is tougher if you like increased control of the settings, for overclocking for example. The best manuals do both: list the jumper settings individually as well as provide a list of processors and the jumper settings for each.
When playing with the board, be careful with it. Avoid placing the board on the static bag it came in, as this can cause an electro-static shock to build up, which may very well fry the motherboard. Always place the board on a flat surface, wooden desks work best, not carpet or anything like that. And always ground yourself before handling the board. When handling the board, handle it by the edges only when at all possible.
1. 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. 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.
- 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 on-board battery is to power the CMOS memory, or an external battery. Again, make sure this is set to the default position (on-board 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.