16 hours ago, bobcat999 said:

Don't take it too badly.  Some people are more tolerant. 
I am guessing you meant which upgrade would be the best for performance in MSFS?  In which case it is not a pure hardware question and it is relevant to the forum as far as I can see.

I never view the hardware forum so I would never see these kind of answers relevant to MSFS performance if it wasn't for threads like this.  And I have learnt a lot recently.
To future proof, I would go with the AMD chips as the X3D chips in particular show massive performance gains in MSFS, which seems to respond to the extra cache on these chips really well.

Personally, I have just gone from a 12900K to a 13900KF, and I am seeing gains better than expected. 
Without overclocking, and with my 3080Ti, I am holding 60fps in general, which I couldn't before. (4K ultra settings, DLSS balanced mode),  
Something like a complex airliner over complex scenery dips to 50-55fps though.  I am hoping freesync will help with that when I get it working properly again (my settings are out somewhere).

Just a footnote: Obviously I could upgrade easily to the 13900, as I keep the same motherboard and RAM. 
Next year I will look at an AMD 7 series X3D, but with this comes the cost of a new motherboard and RAM - not cheap!
The aim is to hold 60fps in all circumstances at 4k decent settings.  My 1080Ti is only hitting about 80% at the moment, so CPU main thread is the limiting factor currently, but much better with the 13900, as it tops out at 100% on the main thread(s) much less often.

Thanks for the thoughtful response. I wish I could do an upgrade on my existing motherboard, not just for saving the cost of a new motherboard but also the hassle of disassembling the whole computer for the upgrade. However, I am currently on an Intel i9 9820X and the maximum processor my motherboard will take is an i9 10980XE, which is expensive and only gives me a 5% single-core improvement. I've learned the hard way with MSFS that single-core performance is VERY important. Based on what I've heard I think moving to AMD may be a good idea.

I just took the plunge today to upgrade my 9700k/3090 and went for the 7950x.  The logic I used is for the very minimal gain I'd get now from the 13900 over AMD's offering (which I think should be very negligible with a 4090), I get at least 2 or 3 generations of upgradability in just swapping out the chip. I should mention that the price on the build with the 13900k was nearly identical.

Edited December 2, 20223 yr by do_denver2

The 790 MB ihs cover is stamped 13xx-14xx, some on redit think this means support for Intel two CPUs 13&14 Gen.

And a good example of how important the CPU is in MSFS. Same GPU in Games not as big and playable but in MSFS the CPU has a bigger effect.

  i3 12100F vs i9 13900K in 4K on RTX 4090 - YouTube