Starfield REAL Minimum Requirement, budget or old cards? GTX 950, GTX 960, GTX 970, GTX 980ti

Starfield supposed minimum requirement is at 1080p 30 FPS low...But for the budget gamer, it should be 720p 30FPS low. Since Bethesda didn't publish the Minimum Requirement for 720p, let's try to find it out.
Platform was on a quad cores 4th gen Intel i5-4690 with 16G of memory DDR3 and the GTX 900 series, the GTX950, GTX 960 4G, GTX 970 and the GTX 980 ti (not the GTX980 which I don't have). I hope this will help a lot of ppl clarify and decide if they going to buy the game or not.