|Second T20 international, Stormont|
|South Africa 159-7 (20 overs): Miller 75*, Mulder 36: Stirling 2-12|
|Ireland: 117 (19.3 overs): Getkate 24; Shamsi 3-14, Fortuin 3-16|
|South Africa won by 42 runs|
South Africa moved 2-0 up in the three-match Twenty20 series against Ireland thanks to a 42-run win at Stormont.
Paul Stirling struck twice in the opening four balls as the tourists struggled to 38-4 before David Miller's unbeaten 75 stopped the slide.
Miller and Wiann Mulder (35) helped the Proteas to a total of 159-7.
Ireland were 43-2 before slumping to 117 all out with Shane Getkate making 24 while Tabraiz Shamsi and Bjorn Fortuin each took three wickets.
South Africa won Monday's opener by 33 runs but they were soon in trouble in the Belfast sunshine after electing to bat first.
Stirling's spin reduced the Proteas to 2-2 and at 58-5 Ireland were still on top before Miller, who hit five maximums, and Mulder put on 68 runs for the sixth wicket.
South Africa managed a solid total with Stirling (2-12) and Mark Adair (2-33) the best of the Irish attack.
Ireland opener Kevin O'Brien departed with just a single run on the board but it was the dismissal of Stirling, whose 19 took him into the top 10 run-scorers in T20s, that sparked the Irish collapse.
George Dockrell (20) and Getkate provided middle-order runs but the hosts lost seven wickets for 54 runs to leave them 99-9.
Adair (15 no) put up final-wicket resistance but Ireland, as with the first T20, fell well short of the target.
Shamsi followed up his four-wicket haul on Monday with 3-14 while Fortuin claimed 3-16.
The teams will meet for the final game of the series at the same venue on Saturday.
"The bowlers bowled really well and put us in a position that we could have chased," said Ireland captain Andrew Balbirnie.
"It's just disappointing that we couldn't put a partnership together - a big partnership that could have gone a long way to chasing the score."