Personally, for flight sim, I'd go nvidia. Flight sim isn't a fast game and the 4000 series frame gen and dlss work exceptionally well with it...you'll get a massive bump in fps and smooth gameplay. There's not that much difference in price or perfomance with e 7900gre or a 4070super...and 100% go with the 7800x3d for vcache, which also flight sim loves
Side note, the rm850x shift psu is on offer at the mo for £130 which is only £5 more than the rm850e, and is a better psu(warranty goes up to 10yrs from 7yrs also as a bonus)...the connections are on the side of the psu rather than the back(which make it easy for plugging in/unplugging cables etc)...i checked and it is compatible with the case also
Side note, the rm850x shift psu is on offer at the mo for £130 which is only £5 more than the rm850e, and is a better psu(warranty goes up to 10yrs from 7yrs also as a bonus)...the connections are on the side of the psu rather than the back(which make it easy for plugging in/unplugging cables etc)...i checked and it is compatible with the case also