I have this problem was I first build my mining rig.
I have same motherboard like you the ascrok. and 6 Rx 580 4gb
plug the 6 gpu only showing 5. no matter what I do. from uninstaling the driver to reinstal the windows only 5 gpu.
but I found how to fix it.
get 1 GPU that the I think that GPU not recognized by windows.
plug out all the riser. and put the main problem GPU into the pcie. just put it. without the riser.
after I turn it on. the mining rig seems weird. very long to boot up. but after I wait for a while I got the windwos login. and try to mining with 1 gpu for checking is this GPU still ok or not.
after that
pull this GPU and put them again into riser and put other 6 gpu into motherboard. and walla. it work. 6 gpu recognized by windows. and mining until now..
sorry my english so bad.
Thank you very much! Your English isn’t bad, I understood completely, I will try that out. Thank you again!
I will see if it works, hopefully.