[Request] MPG B550I Gaming Edge Wifi force PCIe Gen 3 in default settings

Hello,

I’m posting here to determine if there’s a way to edit the BIOS of the MPG B550I Gaming Edge Wifi (can not post the link) so that PCIe Gen 3 is set instead of Auto (and Gen 4 for that matter).
There’s a PCIe 4.0 riser cable in between the PCIe x16 slot and the graphics card (RTX3070) and it’s just unstable/unusable when it randomly succeeds to display something or just a black screen since in the default Auto mode the motherboard selects Gen 4. So an old card is needed just to get into the BIOS and force Gen 3.
If the BIOS gets reset, it’s back to no screen every time. I contacted the riser manufacturer and MSI but it seems the MSI motherboard is just not stable in Gen 4 with the riser cable.

In the BIOS the setting in question is under Settings > Advanced > PCI Subsystem Settings > PCI_E1 Gen Switch and there’s a choice between Auto, Gen 1, Gen 2, Gen 3 and Gen 4. So basically I’d love for the default settings to force Gen 3 by default instead of Auto here so that when it resets, I get a working system. But I’m out of my depth on where to look for changing the default settings.

The latest BIOS 7C92v15 : (can not post the link)

MPG B550I GAMING EDGE WIFI bios version is 7C92v15 (2021-01-26)
your product is still supported,i advice against modding your bios.its highly likely that they will release further updates for this device,therefore your modifications will not be permanent