gpu asus hd 7790

Hi all i'am stuck the question to all is i bought 2 hd 7790 gpu 1 is (asus) other is (h.i.s) gpu the asus works on msi z87 g43 m/b pcie 2 not 3 but H.I.S. gpu works on pcie 3 on the same m/b psu is Enermax Noisetaker EG701AX-VE(W) i know it's old but still works and got plenty of juice in it can anyone help please

Is the motherboard BIOS up to date?

What is exactly the question? - why they don't work? Or would they work? Or the PC refuses to boot all together?