I agree - I think the monitor is the issue.
I tried setting it to 1080p, but I believe because the game is locked to fullscreen when I alt-tab out of the game it goes back to 1440p OR ends up only in the part of my screen which 1080p covers.
Both are bad in the middle of a game... Or anytime really.
Answer someone suggested which I'm using is MSI Afterburner. This comes with a utility called 'Rivatuner' which I can use to cap the fps on individual programs. I've capped Ashes at 30fps now.
So instead of it running at 45fps but struggling to get 28fps to OBS - now it runs at 30fps and that extra horsepower is able to keep OBS running at 30fps as well.
This seems to be working and I'll test it more when I play tonight.
Thanks for the help.
-Geo