Well, the GTX 560 is what he uses to play Ark, and he confirms he can play it on medium-almost high, which is enough for me to enjoy it (I do not mind the play dooh graphics)
I do not know what PSU I have, I would need to open the CPU, for now, I am not touching it till I get a decent GPU, it even lags while loading a youtube video, it also made my pc shutdown for playing Runescape plus opening Chrome.
Have you actually seen him playing Ark at those settings? I would estimate that it would only get around 30fps on low settings in 1080p. Your friend may have a resolution that's even less than 1080p which gives him these graphics.
Also not sure why you would need to open the CPU to check which PSU you have. As far as I know, the CPU doesn't even open lol. You're going to need a sufficient PSU so that you have enough wattage to even power your GPU. If you wait to get a decent GPU and don't have enough wattage, you will be extremely dissapointed when your computer won't work right.
Finally I still wouldn't buy the 560 as it's absolutely a terrible deal when you can get a card that's much better for the same price. It just wouldn't make sense to go any less than a 950 for your needs.