bro, its about your drivers,
install 16.11.2 driver,
if it not fix; try
first close the automatic ''driver update'' (and also windows update on windows) (there are videos on youtube about that, its easy)
download the ''16.11.2'' here:
http://support.amd.com/en-us/kb-articles/Pages/Radeon-Software-Crimson-Edition-16.11.2-Release-Notes.aspx 16.11.2 is important, do not use timely new drives on rx470 and rx480,
if it not fix; try
restart and install DDU, (you can delete the drivers with this program). delete drivers (close the driver update, (i m not talking about windows update, driver update is a diffrent thing. ) restart and install 16.11.2
dont change the riser socket position everytime on mobo,
sorry about my english
if you have headache again fell free to asking here or PM
Man i really appreciate your reply but i tried that and nothing :S, in fact the problem is not the 5th GPU, the issue is the pcie x16, when i use my 4 pcie x1 everything is fine.
my mobo is Asus Prime H270 PLUS
5x Asus Strix RX 480 8 GB
4GB RAM
Celeron CPU