I know its a really newbie question as far its contents are concerned but i wanted to ask can an old generation PC support the proper capabilities of a gigabit internet connection. Or does having a gigabit internet require a gigabit modem in the PC as well?
You’d need to define what you mean by old generation. But to answer your question in a generic way, in order to support gigabit internet, the whole thing needs to support gigabit speeds. If any part of the system doesn’t support gigabit speeds then that will be the bottleneck.
To me, old generation PC would be one that would use a serial port to communicate with the modem, in that case, I don’t believe a serial port could process gigabit input.