To make the installation easier, you should set all jumpers and dip switches while the new motherboard is outside the case, along with the CPU and memory. Refer to the motherboard owners' manual for the CPU and memory settings. Many motherboards will automatically set the correct values, making the job that much easier. It is best to start out with the recommended settings, even if you are planning to overclock, just to ensure that the system works properly when running within spec.
The new motherboard may have the standoff holes in different locations than the original board, so you should identify them at this time. The holes that have a silver insulator surrounding them can accept either the nylon or brass standoffs, while those without the insulator can only have the nylon standoffs inserted. Be sure that only the holes that correspond with a slot in the case have a standoff inserted.
Carefully lower the motherboard into the case or onto the removable rack to identify which holes in the motherboard will contain the standoffs. If you find that one of the old brass standoffs in the case does not have a corresponding hole in the motherboard, it must be either moved or removed. Direct contact between the motherboard and the case (or anything attached to it) can cause a short circuit and possibly even damage the motherboard.
If the new motherboard is a different length than the original, it may not have any support at the front. This is not a problem, as the only requirement is that the motherboard does not touch the case. If you prefer, you can remove the tab at the bottom of one of the nylon standoffs so it will sit flat on the bottom of the case.
Insert the nylon standoffs into the motherboard from the bottom, making sure to push them up until the clips snap into place. Lower the motherboard into the case or onto the rack so that the tabs on the standoffs drop into the proper holes, then slide the motherboard into place. Insert the screws into the holes where the brass standoffs are, and secure the motherboard into place.
Reinstall any drives or other components you may have removed to get the motherboard out, then attach the cables and wires to the motherboard. Many cases have wires that are not used on current motherboards, such as Turbo LED and Turbo Switch wires. Tape them or tie them in a knot and secure them to the side of the case. Double check that all drive cables are oriented so that the colored edge corresponds to pin 1 on both the motherboard and the drive.
You will need to attach the parallel and serial cables if you have an AT style case. Do not use the cables from your old motherboard, because not all manufacturers use the same pinouts for the serial ports. Using the old cables may cause problems that will make you think the motherboard is defective.