vga compatible with all GPU after flash of rx 480..

Dear all,

I am having some troubles with my system lately (windows 10).

Everything started with the flash of a gigabyte rx 480 8g. The flash went well and after the reboot i faced the error 43...
I tried to solve this with tuto that describe how to disable the signature checkup of the driver.
It did not work.

So i decided to launch my linux and this time my card was not visible and my system did not find any gpu.
(It found the card but as a generic model that does not need AMD driver).

I tried to switch back to windows and now i am having just a vga compatible card...
I switched the 480 8g with an old and untouched r9 380 and exactly the same..

I decided to make a fresh install (windows 7 this time) but the problem is still there...

From this i guess that it is the motherboard (BIOS UEFI) that block my cards..

If someone had this problem and solved it...

thanks,

K.