dunno man, my corsair 550w has zero issues with my OC 1080 and any games (VR and destiny 2 included) as well as mining when I'm at work which puts my GPU to 100% usage for hours at a time.650W is probably not enough for everything and the 1080. I'd bet a dollar that if you swap it out for a quality 800W or better, D2 would be stable. I'm not sure what it is, but Destiny 2 pulls some serious juice out of my rig. What led me to believe it was the power supply was the symptoms you were mentioning.