Cardiff took an early lead through Guillaume Doucet, but John Armstrong quickly brought Sheffield level.
Joey Haddad and Joey Martin ensured the Devils finished the first period on a high with two quick goals to make it 3-1.
Sheffield roared back in the second session with goals by Geoff Walker, Colton Fretter and Levi Nelson turning the game on its head.
Cardiff regrouped and drew level at 4-4 through Layne Ulmer, but Walker grabbed his second of the game in the 37th minute to put Sheffield back in front at the second break.
Andrew Hotham tied things up again early in the third period and although Ben Bowns was forced to make a wonder save late on, overtime was needed to split the teams.
Neither side could find a goal in the opening session, with both netminders making some fine saves.
The Steelers eventually broke through in the 96th minute when Nelson fired home to make it 6-5 and end Cardiff’s Grand Slam hopes.
3rd/4th place play-off
(Image permission: Dean Woolley)