SYSTEM BOARD: How to fix system board that does not boot properly...

Problems with the system board can cause the PC to not boot properly or can cause the system to be unstable, producing intermittent errors or causing the system to hang. Problems with other devices or with software can cause these same symptoms, so  troubleshooting the system board is only one of several things to do to locate the source of a problem. Here is the list as your troubleshooting tool to identify and solve problems with a system board:

Is The System Board Newly Installed?

If this system is newly installed, then check the installation to very that:

• Jumpers are set correctly on the board, Reread the system board documentation and verify that the CPU, bus clock speed, and cache memory jumper setting are corrects
• Verify that the system board is securely mounted. check these things 

                     1. The board cannot move in the case. You should not be able to move the board when you lightly push on it.
                     2. The board can't  touch the bottom of the case, Spacers should be located along all sides of the board and no bare wires touch the board.

• There are no loose screws anywhere inside the case.
• Check  for loose wires or cables in the way of the CPU fan.
• For ATX system board, check the power wire from the front of the case to the system board. Verify that it is not frayed,bent at sharp angles,or loosely connected to the board.Verify that the wire is connected to the correct pins on the board
• Verify that all wires to the system board are connected to the correct pins

• For AT system boards, verify that P8 and P9 are correctly connected using the black-to-black rule. (Black wires on P8 and P9connections are side-by-side.)
• Remove the system board from the case and look for frayed,scratched,or damaged places on the board. A trace on the system board may be bad.
• Reseat and then replace memory modules.
• Reseat and the replace the CPU.
• Replace the system board.

Symptom: The system is generally unstable

• Troubleshoot the electrical system to eliminate an electrical problem before you continue here.
• Verify that the CPU fan is running and the system is not overheating.
• Verify CMOS setting. A low battery could cause correct CMOS setting to be lost.
• First back up CMOS setting and then restore them to default setting.
• Check that the power connections are secure
• Check that the CPU is seated securely and that the fan is attached firmly.
• Remove the system board from the case and look for frayed, scratched, or damaged places on the board. A trace on the system board may be bad.
• Replace memory modules.
• Replace the CPU, If this step solves the problem, try the old CPU again. The Old CPU might not have been seated correctly.
• If the system board has a diagnostic CD that came from the system board manufacturer, run the diagnostic programs.
• Suspect virus that has damaged BIOS, try downloading a new set of BIOS programs from the manufacturer's Web site.
• Replace the system board. If this step solves the problems, check jumper and CMOS setting on the old system board, which might be the problem.