After about 12 months of using my hand-built computer, it is becoming slow. I want to wipe my hard-drive and start out fresh. My question is is will i be able to reinstall Windows 7 OEM into the same computer, same parts. Will i need to activate it by phone support?
Technically, you weren't allowed to install it in the first place. OEM licenses are specifically for computers to be sold. You are not allowed to buy an OEM license for yourself or anyone in your family.