Monitor Orange Light

hen i power on my computer the computer on but the monitor goes to green light & then after 2 or 3 seconds it shows an orange light. The power fully fans works ,Hard disk light ,CD Rom as well works but at start it does't show any display .The SVGA card is also built in on the Mother board. All cables are connected properly .Plz guide me that where should be a problem. In short the i can't see the any thing on the monitor even post .The monitor is also ok So what step should i take to see POST on my monitor and the orange light switch to Green?