Everything’s got this shit green tint.
Unless you're making some Nvidia = green joke, that's some setting on your side. The crashes might be as well, some unstable overclock or PSU issue.
The main things that's been plaguing the Nvidia drivers is black screens, which are seemingly finally getting under control for the last two driver releases, along with Windows Updates.
Value of the 50-series is definitely shit though.
Ok, but what if...you just kill bosses in five hits, because they don't have any HP?
It's an overexaggeration of course, but the enemies definitely have a lot less HP than in coop, not even just 1/3 or whatever (seemingly).
Also, are the enemies designed for multiplayer, except in scaling? Everything I've seen looks like standard Fromsoft stuff, no weird abilities that just fuck over solo players.