Do I need to reinstall Windows after swapping motherboards and upgrading components?

For the motherboard swap, you're in the clear—no Windows reinstall is needed since all the drivers will be compatible. The CPU upgrade also doesn't require a reinstall, but do make sure you have the latest chipset drivers. When you start the computer, the Nvidia drivers won't activate since the new AMD card isn't recognized. It’ll revert to basic display until you can install the correct drivers. For a clean installation, you're right—you need a USB drive.

You shouldn't need to reinstall Windows just for swapping the motherboard, especially if it's the exact same model. Changing the processor also shouldn't require a reinstall since there are no specific CPU drivers. For the GPU change, you can boot up just fine with the old Nvidia drivers; the system will use basic display drivers for the AMD card initially. Once you're up, just use DDU to remove the old Nvidia drivers, then install AMD ones after that. As for clean installs, you'll need a USB drive for that.

With all the hardware changes you've made, it's probably best to perform a clean install to avoid potential issues later on. Plus, doing so can prevent any hidden problems caused by leftover drivers. And yes, you'll definitely need a USB drive for that clean installation.

There are a couple of things to keep in mind. First, depending on your Windows license type, changing the motherboard could affect activation, so it’s good to note down your activation code just in case. Also, if you were using secure boot, make sure to save the secure boot keys before making the switch, or you might run into boot problems. As for reinstallation, you'll need that USB for a clean install.