MSI GAMING X RX 470 8GB BIOS is different GAMING X RX 470 4GB
Overclocking memory TIMING is different.
You need prepare software as below :
(1)AMD/ATI ATIFlash 2.74 (link) : For save BIOS and flash BIOS
(2)PolarisBiosEditor (link) : For edit BIOS
(3)GPU-Z (link) : For display Graphics Card status
(4)WattTool-0.92 (link) : For Overclocking GPU