I often see old questions (from the time before superuser.com and serverfault.com) that are offtopic. But they are not closed.
It doesn't make sense to vote-close on them, since no one else will see the question and vote-close, so it will never get five votes.
What should I do with old questions that are off-topic?
Does it make sense if I flag the question for the moderator, or will this just be noise for the moderators?