|You gave us very little to go on. Please post your complete system specs. Are you hearing any beeps? Do you have a case speaker connected to the board?|
To troubleshoot, disconnect ALL the non-essentials. Unplug all external devices except for the keyboard & monitor - no mouse, internet cable, printer, external drives, etc should be connected. Internally, unplug all drives (DVD, HDD) & remove all but one stick of RAM. If you have a video card installed but your board has integrated graphics, connect the monitor to the onboard port & remove the card. The idea is to lighten the load & eliminate as much hardware as possible. After disconnecting the above, try booting the system...if you can get a display, enter the BIOS & double check the settings. While you're there, check the CPU temp for overheating.