turns out, 2 years ago when I set up .161 I was running this monitor at 1920x1080. I have since then switched up to 4k, which runs at 30hz on hdmi. SO nothing wrong with mame, just the user running it.
If I drop back down to a rez that runs at 60hz, then vsync works just fine. Thanks all for steering me in the right direction.
(now i need to look for my DP cable)