How Can You Tell If Your Motherboard Is Fried?
If a computer is dead or struggling to boot at POST (power-on self-test), all other possibilities for the problem must be eliminated before assuming the motherboard is fried. One surefire way to do this is to replace every component on the motherboard---with the exception of the CPU---with known working or new components. If the PC remains dead, the motherboard is fried. However, if you prefer to work with what you have, performing the procedures below will help you determine if the motherboard is fried by eliminating all other possibilities.
Often a dead computer is the result of a single bad connection and not a fried motherboard. This can be checked by reseating the RAM, cable connections, and expansion and controller cards, hard drive, and all storage devices. If the PC reboots normally, it is likely that a component had come loose or was not seated properly and the motherboard is fine.
If the computer refuses to start or boot after reseating the components, the problem may be with a faulty card. This can be checked by removing one card at a time not required for boot and restarting the PC. These cards include the sound card, modem, network card and any extra added controller cards. If you remove a card and the PC reboots, you've found the problem. If you've tested all cards and the PC is still dead, the chances are good your motherboard is fried.
Check Voltage Output
Overheating from a faulty power supply is probably the biggest cause of an overall fried motherboard. Sometimes---but not all the time---you will notice physical damage to the motherboard itself, including burn marks or fried capacitors. If, by eliminating all other possibilities, you've determined the motherboard is fried and needs to be replaced, test the voltage of your current power supply to ensure it is not producing too much power. If there is any doubt, simply install a new power supply along with the new motherboard to avoid any future issues with overheating.