PCIE 4 implementation on the motherboard bridge vs PCIE 3 on the B550… apart from that the feature set is similar with both having PCIE 4 coming from the CPU.
So most X570 boards will have all interconnects supporting the faster transfer where as you will only get the PCIE 4 support running through the CPU and if you use the motherboard its going to be PCIE 3 on the B550 Chipset
practical example … My motherboard Asus B550 F gaming Wifi has two M.2 slots … one is PCIE 4 and supports the fastest speeds via the CPU bridge and the other is run through the chipset southbridge and runs at maximum PCIE 3
On the X570 Boards both the m.2 slots will all run at PCIE 4.
Thats pretty much the essential difference and in “typical” real word use its not a handicap because the data transfer speeds are not being saturated in full so i went with a decent quality properly specced out B550 board rather than a low spec X570 board.
Thanks all for precious replies.
I came back to give an ex post facto report about my build.
My new system and test condition are like:
12700K, 3070Ti, 32Gb DDR4 3600CL16
UWQHD 3440x1440
SU9@Ultra setting
At the cockpit view of FBW A32NX@KJFK, my fps was of course main thread limited.
The render time was 26~28ms, which translate to about 37fps
At a relatively “relaxing” situation (C152@KSEZ) my fps was GPU limited.
The render time was 17~18ms, failing to achieve stable 60fps.
As I set refresh rate of my screen to 75Hz and applied 1/2 rate V-Sync, my fps is fixed at (almost) rock solid 37fps.
I think it was right choice to get a faster CPU over GPU since the minimum fps is still limited by CPU. (not applicable for VR though) 3070Ti was more than enough to squeeze 37fps for my UWQHD screen. Perhaps it might be able to squeeze same fps for 4K.
