the OEM license provides you can sell it with an essential part of a computer, but cant be things like hdd or cpu etc etc or you can sell it preinstalled with a complete system.
power cable is the cheapest bit of gear that legally fits the obligations.
the limitation of the OEM is it is licensed to that particular machine and if you blow a motherboard in a storm or under warranty you have to reactivate and that normally means a call to their support team and the activation robots and you cant do an upgrade install.

