1. Check for loose connections
2. Disconnect the video card and connect your monitor to the motherboard monitor connections to see if it has the same issue
3. Check to see if the RAM is properly seated in the DIMM slots in the right population. Typically, if the primary DIMM slot is loose, video will not display.
4. Check the cabling of the monitor cables. Do you have a known good monitor cable you can use to test?