SR-71 gave the complete answer. The short answer is no. Windows 8 OEM license allows you to remove it from one machine and move it to another machine. This was technically not allowed with previous OEM distributions of windows, such as windows 7 OEM.
When they say "tied to the motherboard", they mean the license agreement forbids moving to a different motherboard. But it doesn't do anything special to the hardware. Again, that does not apply to windows 8.
OEM editions cannot be used for upgrades. You can do clean install, but not upgrade. Retail edition will upgrade and can also be moved.