Yesterday, i tired to put a new GPU R9 290 in my miner that already had 5 GPUs RX470, but the motherboard was not recognizing the R9 290, then I tried to update my drives and it didnt work... So i realise that the problem could be at the PSU becoes it has just 1000W. So i gave up of trying to add the new GPU, but now my miner just recognize 4 of my 5 GPUS RX470, i tried to format my HD but also did not work, by the way i use Windows 10. Help!
First: probably is the PSU ( try to test 3-4 RX470 + R9 290)
Second: If PSU passes the test, try to run all six GPU with 6gpu_mod app ( search for it on Google)
Third: Change your Graphic driver.