second gpu via pcie x1 to x16 riser only mines 4 mhs

hi guys thanks beforehand because i know you will help me


i have one rx 470 sapphire ref working at 26.7 mhs on the pci express normally.

i have another exactly the same: both sapphire ref and both working at around 26.7 mhs (if used one at a time)

the problem is as soon as i use a pcie riser, and put the second card to make them both work together, that second card gives only 4mhs on claymore.

also when i try to see it with gpuz it says it runs at 0 MHz core and mem.

when i open wattman, all possible options on the second video card are grayed out.

if i try to open atiflash, it shows an error: failed to read rom and atiflash wont start.


but as soon as i remove the gpu and put it as a solo on the pcie x16, both card Works if not used together, wattman can read them, and also, atiflash can open, and they mine at normal rate (26.7mhs).


any help?

thank you very much