system is not booting

[khaja]

i have pc.when i power on the cpu,the cpu is starting the fan is running all lights are glowing ,but it is not booting i mean the monitor is not displaying,there comes the beep sound ,the light of the monitor is flashing but it is not stable.but when i start again after an hour it is working normally after an hour it suddenly turns off (cpu is working ,mouse light is there but no display in monitor).....when i start after several hours from the problem occurs ,,it works normally as nothing happens...plz help me....

[GR@PH;<'S]

khaja,
It may sound silly but disconnect your monitor cables from both your Tower and the monitor, then refit them.
If you still get the same error see if your graphics card is seated properly.

GR@PH;<'S   :Hammys pint: