Plan on having 200 or 300 GB available for Ark. You need space for the game plus quite a bit of extra for when it installs updates (which happen often). You'll also want 16GB of RAM or more. Also, will it run games like fortnite or minecraft java?
I got a new rtx 3070 a few months ago and I got to say the performance increase I was looking for from my previous card (gtx 1660ti) isn't what was expected. The issue is that when I'm playing fortnite (I know lol) I still get lag and fps drops, I play o