Turns out I was mistaken. It's actually a 650W unit. Heres the link: https://www.amazon.com/gp/product/B01LYGFRL6/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1
I was so sure that I picked the 750W model but I guess I didn't. 650W should still be enough especially considering the quality of the PSU but I would understand if it wasn't since I have a lot of fans and storage drives hooked up to it. I do have a 750W CX750M on another PC so I guess I'll try to swap them and see what happens. Now that I think about it, the PSU seems like the most likely culprit to me so far because if the GPU truly was dying, there would be signs of some sort of progression of the problem but that isn't really the case. The freezing still happens as frequently as when it first started and there hasn't been much change in the overall behavior of the PC since the problem started 3 months ago or so. I'll swap the PSUs and report back if the problem occurs again. Thanks again.