The behavior that you are experiencing is usually related to a device not properly recognized.
I recommend you to test your system on a basic configuration and start adding a device at the time until you determine which one is causing this behavior.
To turn on the , you only need the power supply, the processor and a monitor connected. If the system boots normally then start adding devices like th hard drive, optical drive, etc until you find out which one is holding up your computer.
Thanx alot for your kind reply but i have already tried replacing Power supply and turning on motherboard without any devices attached but the issue is still there ,.... i just add one point to our discussion and that is this issue is just appear as i have updated the bios and after updating the bios i have noticed that one extra column appears in bios i.e. PERFORMANCE which was not present in the last version/default version of the bios...is this related to the issue i am suffering with... as i have complained to the computer shop from where i purchased the Computer about this issue.. they says that its normal delay..but question which appears in my mind is that why not it was before updating the bios if it is normal...
Additionally Dear VICTOR BIOS Performance option includes
2)Processor Overrides etc etc
Please help me after a proper research...that can i resolve this problem by myself?..is it normal?..or i should go for a warranty check?..an aunthentic suggession is needed from ur side...