I am sorry if this is a duplicate but I can't find an answer to this question after spending a fair amount of time understanding how the SE sites work.
If I don't get a notification, could I?
You don't receive a notification for every time you hit the reputation cap, but it is pretty easy to see for yourself:
You can see your progress towards the Epic and Legendary badges in your profile if you've set it as the Next badge, and upon clicking the badge you get the rep for today out of 200:
See the reputation overview in the per-site reputation log: meta.stackexchange.com/reputation for MSE.
The first time of getting over the 200 rep you get the Mortarboard badge (it doesn't necessary occur when the limit is reached). The description of the badge tells you there's a limit. In all the other times (except when you reach 50 or 150 days with the rep over 200 to get Epic and Legendary), you don't get any notifications.
When you are getting up votes beyond the rep cap, they are displayed as "empty" up votes in your reputation tab, like the ones you get for the Community Wiki posts, and the new post-repcap up votes, like any other votes, are highlighted.
You don't get any inbox notifications though.
I always know if I'm going to hit the rep cap, because every time I get an up vote before reaching the cap, I click the achievements thing in the top bar (obviously, if I'm around), and therefore see how much I've earned today, hence I know how many reps to go until the cap. So I don't see a point in getting the notification when I reach the rep cap.