This problem might caused by the CPU over-heat protection in motherboard.
Motherboard will automatically shut down the system power when CPU temperature is too high.
You might try to remove all components and unplug all the power cable, then install them again.
System should boot up properly with this procedure.
Please double check CPU cooler has proper amount of thermal grease and locked properly on the motherboard base or socket.
Normal CPU temperature should be lower than 50 degress.
It can be check in CMOS's hardware monitor.
