maybe the admin will move it to that category. anyway tho anyone know how to get these to work with this mobo?

i just bought 6 rosewill gpu risers ( model number is RCRC-18002) and i cant get any of them to work. i only have 2 rx 570s and my monitor wont even turn on when trying to use them i cant even get into the bios. im using a gigabyte 970a d3p motherboard. the gpus only work if i directly place them in the pci e 16x and 4x slot. ive tried a few options in the bios but somethings not right because i doubt all 6 are faulty. this is an older motherboard anyone know what im missing here or what option has to be turned on in the bios? and no its not the famous "enable 4g" because this motherboard does not have that option.