Question Details: I checked all electrical connections and cables and are OK.

Answer:

1. Look at the power supply to determine if the fan is working.If not replace the motherboard to see if the computer starts.If the fan is working, try another power supply anyway.

2. Shake the case and listen for loose metallic objects that may cause you computer to stop starting.

3. Inspect the motherboard for broken or burnt components.

4.If you hear beeps when you start your computer try to decode the beep code using the internet.

5.Try a different video card.

6.See if the CPU and memory will work with another motherboard.if yes it means that they are not damaged.

7.Replace the motherboard.If the computer starts it means that your motherboard was damaged.