Six of the changes are in the backline, and five in the pack, as several players from the British & Irish Lions series, return to the side.
The only players who started in the first Test 32-12 win are captain, and flanker, Siya Kolisi, lock Lood de Jager, who will play his 50th Test, No8 Jasper Wiese and halfback Cobus Reinach.
The backline selected is the same unit that won the final Test against the Lions. Outside Reinach is Handré Pollard at first five-eighths, Damian de Allende and Lukhanyo Am in the midfield, Makazole Mapimpi and Cheslin Kolbe on the wings and Willie le Roux at fullback.
Lock Marvin Orie will have his first Test start while Malcolm Marx returns at hooker, and Trevor Nyakane and Thomas du Toit are the starting props. In the loose forwards, Kwagga Smith has dropped to the substitutes with Franco Mostert starting.
Coach Jacques Nienaber said, "A few players didn't play last week after a physically demanding Lions series, and are now back in the mix while we also wanted to give a few new players, who have worked hard at training over the last two months, a chance to get some valuable game time.
"This is a long season, so we need to get the balance right between building consistency in selection and in our performances, managing the players in terms of their workload, and building depth within our squad."
They were expecting Argentina to make a strong statement in the second Test.
"Argentina plays with a lot of passion, much like we do, so they'll want to show their fighting spirit, which will set the scene for another challenging Test match between us.
"While we were pleased with the victory and to start our Rugby Championship campaign on a winning note, there was a lot of room for improvement in our performance," he said.