The problem is some of the hashrates are incorrect.
A 7970 will do 730 max.. a 7850 with half the shaders will do exactly half of that *MAX* (or 365). And when I say max, I mean max.. a 7970 at 730 is extremely difficult to hit.
so while I don't have any 7870s, I can tell you 400 is practically impossible unless liquid nitrogen cooled.
I have several 7850 they can get a max of 403 and have 5 running in one board. All 5 get 380-385. . I have 2 7870's too. Those cards were hard to get configured. I spent a lot of time messing with them and can get 360 max out of them. I have 2 7970's also they get 660 max