Sounds more like a bad PSU instead of an under-powered system. I've got an i5-8600k/2080Ti/32GB RAM/960 Evo/2 Crucial MX500s on a 750W TT ToughPower. I ran SLi'd 1080Tis before this too on the same PSU.
The larger PS did fix the problem. But there is no way I had 3 bad power supplies, considering that I'm using one of them right now. They were simply being overloaded.
My point was the game was demanding of power. Possibly the graphics card was using most of it?
Most of the power, definitely. A 2080 TDP is 215w but despite all the power we get now, the power draw isn't bad at all. Anandtech reported under 400w loaded draw for their system (i7-7820x, 16GB RAM, 1TB SSD, 2080FE). You'll need some sort of power meter to see the most accurate draw from the wall but you definitely should have been fine with a well-built 550w.