The system is power cycling, there is a vid in the link.

Welcome to the forums.

There are quite a few things that can cause the behavior in the video you posted. I will list some of the more common culprits in a new build:

1. RAM not seated properly or incompatible with the board

2. CPU has bent pins or is improperly inserted

3. PSU is not adequate for the power requirements of the system (make sure your PSU isn't a multi rail model)

4. BIOS corruption (should be correctable with a full CMOS clear)

5. GPU not seated correctly or GPU power leads not connected properly

6. 8pin CPU power connector is not connected or the wrong lead is connected (PCIe 8pin forced into the 8pin CPU socket for example)

7. Bad CPU (IMC dead)

8. Bad motherboard (RAM slot/s dead)

Pull everything from the board, double check the CPU for bent pins, reinstall everything carefully and make sure the RAM is seated all the way into the slot. Only use the bare essentials, one RAM module, CPU, 8 and 24 pin power to the board, GPU and it's power connectors. Try the RAM module in each slot.

7 and 8 on my list are the least likely culprits and should only be considered when all other culprits are ruled out.

Let us know how it goes 

keeps turning on and off