Upgrade Query

[EsaT]

B550 2 x m2 gpu runs at x8

At least MSI B550 boards don't share main x16 slot's lanes with anything.
That would need PCIe v4 capable switches, which are no doubt expensive, besides no doubt causing major extra cost for PCB to keep signal integrity inside limits.
So second mechanically x16 slot is likely connected to chipset and electrically max x4 in all B550 boards.

 

[Quartz]

If I wanted to add a Soundcard to the mix, would that be problematic?

If you do find that the motherboard sound isn't good enough, consider a USB or HDMI sound device to keep the sound digital as long as possible.

 

[CuriousTomCat]

Brill, thanks Micky I think I'll stick with my 650W and see how it performs in that case!...

How old is your 650W PSU? Nvidia recommends a 750W for the the 3080 Founders Edition for be careful. I understand that you're trying to save money but this can be done in other areas such as a 3070 instead of a 3080. Or onboard sound instead of a posh external sound card.