Motherboard spoils is not an obvious problem. A lot of symptoms
are very similar to motherboard spoilage. Hard disk is pretty
obvious, when they ask you to put in a hard disk or when the
computer beeps a certain pattern indicating that there's no hard
disk.
As for your problem, please list out the specifications of your
PC.
An OS is an OS, Microsoft doesn't differentiate them. Microsoft
will only attempt to tell if the OS used is legitimate.