I am building a new computer and was unsure about how I should approach the OS. I purchased a Windows 8 Pro Upgrade disk from Newegg brand new on a back to school sale. My understanding was that it would work on my build with my motherboard being brand new right out of the box. I was just told that this was not the case and would greatly appreciate if anyone could give me a definite answer. Will my Windows 8 Pro Upgrade disk work on a fresh mobo right out of the box with no existing OS on it?