I saved 1 out of 2 GPUs that was buggy! How? I've unplugged all  GPUs and try plugging one of the buggy GPUs directly in PCI-e x16 slot instead of risers, after a black screen of 10 minutes, Windows finally saw the GPU and displayed the image of Windows. After, I've replugged this GPU in the same riser and in the same PCI-e slot it was before and it's working well. So now I only have 1 faulty GPU which is still under warranty with MSI, I am brining it to canada's computer tomorrow to see if they can do something about it or else I will return it to MSI.