Follow stekusteku advice
Buy a great GPU, period
so many people taking cpu… i bet a 12600 is more than enough for a 4090… everything.max in msfs settings and vr and at 200% wmr
Buy a 4090, a 5800x3d or 13600k, good aircooler (67mm min, 57mm not enough), cheap mobo and ddr4 or 5 able to manage gear 1 at cl16, 3600 (this avoids stutters)
Ddr4 vs fancy expensive ddr5, not important
Pci 3 vs pci 4, not important
liquid cooling and overclocking, not necessary
750w power supply more than enough, a 4090 should not work over 375-400w.at full load if properly undervolted
you will enjoy msfs