Answer:
Your processor might be incompatible with motherboard
Explanation:
One major thing to keep in mind while upgrading a PC hardware is comparability among hardware. If you are using incompatible hardware it can cause issues like this. There are websites available to let you check the compatibility of different components.
As you mentioned you upgraded your cpu and motherboard. Does your motherboard has the correct version of chipset to run new cpu. Do notice if there are any beep sounds when you power up your PC. If you don't hear beeps than your motherboard might be dead.