South Carolina was a founding member of the conference and left in the 70s over the "800 Rule". The ACC had a rule that in order to get a scholarship, an athlete had to score at least 800 combined on the SAT. USC-e didn't like that idea because it hurt their recruiting and also didn't like the power the 4 NC schools had in the conference, so they left. (Their 4 votes effectively shut down any changes because USC-e, Clemson, UVa, and UMd couldn't get any of them to join them to form a majority on any votes.) Georgia Tech was brought in to replace them. GIT had been an independent after leaving the SEC over academics.