Hadleigh O'Leary still lost a series of partners before he too fell in the 17th over, but Hadleigh Reid (18 not out off 15) hit three boundaries in the tail to get Marist up to a defendable total.
Adam Beard, Adam Lennox and Kobe Lee all took one wicket each for Collegiate.
In reply, the schoolboys top order impressed to make their way to 115-2 in the 17th over, with all four batsmen contributing.
Lennox (19) and Shaun O'Leary (34) put on 32 for the opening wicket, before Tom Redpath (2-24) separated them, with O'Leary then carrying on with William Hocquard (24 not out off 23).
None of the other four Marist bowlers could provide a breakthrough, and although Redpath getting O'Leary at 79-2 after 13 overs gave them some hope, skipper Harry Godfrey (23 not out off 14) came in to swiftly hit four boundaries and wrap the game up in quick time.
At Victoria Park, United welcomed back pace bowler Ryan Slight (2-8) to have immediate effect as he got two nick behind dismissals to reduced Tech to 5-2 early.
Quinn Mailman (15) tried to shore up his end, but rapidly lost partners as the veterans Ritesh Verma (2-13) and NZ Over 50's spinner Martin Pennefather (2-16) pinned them down and chipped them out, leaving Tech at 21-5 by the 11th over.
Peter Czerwonka (16 not out) and Jordan Healy (29 not out) prevented their side from being bowled out, with Healy hitting three boundaries to at least score at nearly a run-a-ball, but 69-6 at the end of 20 overs was never going to be enough.
Andre Canderle (17 from 12) looked to get after the small total early, as did each of the United batsmen coming in – all of them hitting at least one boundary – although they also got out swinging with Tech coach Chris Friedel (2-21) getting the prize scalp of skipper Simon Badger (10).
Stephen Holloway (12 not out) hit three boundaries in the space of seven balls to see his team to the small target in the 12th over.
Scoreboards
Marist 114-7 (H O'Leary 24, C Stewart 22, H Reid 18no; S O'Leary 3-32) lost to Collegiate 115-2 (S O'Leary 34, W Hocquard 24no, H Godfrey 23no, A Lennox 19; T Redpath 2-24) by eight wickets.
Tech 69-6 (J Healy 29no, P Czerwonka 16no; R Slight 2-8, R Verma 2-13, M Pennefather 2-16) lost to United 70-4 (A Canderle 17, S Holloway 12no; C Friedel 2-21) by six wickets.