If you change the motherboard and processor there are going to be a LOT of different drivers required. More than likely the PC will not boot because Windows is going to try to load the OS using drivers of hardware that doesn't exist any more. You'll have to do a new install of Windows. Back up your stuff on something else first, then do a fresh install. If there's a problem with your Windows install worst case scenario is getting a new copy of Windows 10 from Kinguin.net or something. You can get the pro version for around 29 bucks. It's just the key though. You have to download the install files from Microsoft and put it on a USB or something. (I actually bought 4 of them so far and they work great)