graphic card or monitor ?

have a small problem with my monitor when the pc is off the monitor flashes amber and when i boot the tower up nothing happens the tower boots up but the monitor stays amber ,when i press the on/off button the monitor light goes green for a second the reverts back to amber but if i switch the whole system off at the power point and leave it for 5 to 10 mins and boot it all back up the tower and monitor all come on , iam nearing a nervous breakdown with this so any help would be greatly accepted