Should be okay with that PSU but you're skirting the limit. Nvidia recommends a minimum of a 700W PSU but that assumes that the PSU is the bare-minimum quality. I guess you try it and if your PC crashes under load or just trips itself off you know you need a better PSU. As
@droopyRO says, you'll need an adapter to power the card and if you're buying used you need to make sure it's included (all RTX cards with the 12-pin cables came with adapters for 8-pin cables in the box, without exception).
Is the 3600 CPU a bottleneck? For high-FPS gaming, absolutely. For single-player games with all the settings cranked to max on a 144Hz monitor or lower, it shouldn't matter too much. It wouldn't hurt to drop a 5800X3D in there though, it's a huge improvement over the 3600 and given how much you've spent on a 4070 Ti Super, probably a worthwhile investment.