1. Make sure that the CPU is supported by the motherboard, check the CPU Support list on the manufacturer website.
2. Check for visible bent or broken pin(s) in the CPU itself.
3. Check memory requirement and memory installation, make sure the RAM stick(s) are seated properly.
4. It is always good to test the board with a single stick to rule out a single bad stick of memory.
5. Make sure that the ATX 24-Pin and ATX 12V 4 or 8-Pin are plugged in firmly into their sockets on the motherboard.
6. In case you have installed an graphics card on PCI slot, please check if the card requires additional powers 4, 6, or 8 Pin PCIe power.
7. Test the motherboard on a non-conductive surface or test bench to rule out the grounding possibility. It is a good practice if motherboard and other components are tested on test bench before putting in the Chassis or computer case.
8. Check monitor for video input selection, VGA, DVI, or HDMI.
9. Check the VGA/DVI/HDMI cable and ensure that cables are not malfunctioning. Test with other video cable.
10. Avoid using any video adapter or KVM switch.
11. Clear the CMOS by taking out the CMOS battery from the battery socket on the motherboard, leave it out for 5 minutes and place it back. Make sure that positive side of the battery faces up.
12. Some motherboards like Asus Maximus series boards have dedicated clear CMOS button which comes in handy for the step 11. Not all motherboards provide this support.
13. Ensure that power supply is not malfunctioning. For this purpose test the power supply by using either of the methods described below:
Test Clip: Watch the video on how to use paper clip for testing:
Test Clip Vid
Voltmeter: Use a voltmeter, if available, to test the power supply. Watch the video:
Voltmeter Test Vid
14. Ensure that your power supply has sufficient juice to supply the power to your system. Check this video on determining how many Watts does your system need:
With these steps, it is most likely that you will solve the issue.