Got some good news ! I could made it work ! I'll copy what I wrote in the netbookreview forum, and hope it'll serve to somebody here
Hi there !More news here : With the "Rx 480M 4GB vBIOS - 015.050.000.001.000000 Samsung & Hynix TDP70W.rom" vBIOS, the problem seems to come from vulkan/DirectX API.OpenGL games works great (Portal 2 and Hades via wined3d) without crashed under linux.It seems so that this bios doesn't permit me to use the vulkan api (under linux) o directX under windows (the crash with heaven benchmark using directX11).I tried to search a bit but couldn't find any information : Does anybody have a link about vBios modding or want to play with me at the "Will your computer burn if you install that" game ? Anyway I might speak alone, but at least if somebody pass through the same problems, he/she'll have here a bit of information.
Even more news ! I flashed another BIOS from here --> https://linustechtips.com/topic/126...esartifacting-problems-when-its-underclocked/which seems to work a bit better, but I steal got the same problems with vulkan (I used the one named 700).So I thought, why don't I give a try with this poor Windows that I everytime forget and then tadaaa : Directx 11 and Vulkan work there.Weird thing, this bios seems to be from a rx 580.I tried with the same game "Hades" which can run with both api.So we could say that a rx 480 mxm can work within a Gt60 Ol' Laptop, wich is great IMO, I'll upload here the vBIOS I got from Internet in case of somebody might need them.ANYWAY, if somebody want to help me with the linux problem (still searching for a solution), I'll be honored .
Oh, and a last detail, but of importance : My motherboard BIOS is flashed.I remember doing it a long time ago (years), seeing a thread about putting 980m inside my mobo. I flashed it in case of, but i can't remember where i found the file.Anyway, the bios name is E16F31MS.51X (yes, it's from another motherboard, but it's compatible) and the EC is 1762EM71 ver 4.05.
Here's the link with the vBIOS I've found :https://drive.google.com/file/d/1q9K0j7zgLCMHvHXzaoZIDzJyjk4V29LX/view?usp=sharingIt's a zip archive, hope it'll serve to somebody