16gb is enough for 1440p unless you move to 4K and start pushing all sliders to the right then it becomes a problem.
For my 4070 texture resolution to high instead of ultra. I also lowered my texture super sampling to 4X.
Some airports I have to lower my TLOD from 200 to 150.
Thanks for the reply !!
Have you experienced any stutters with your 4070 ?
Are you flying IFR online (airliners, VATSIM) ?
The latter is going to depend on what CPU you have. Not so much on the GPU.
Just go for it and tell us what happens! 
I guess Iāll be the odd one out here. The 4090 is going to be overkill in most scenarios, so is a waste of money in my opinion. The 4080 and 7900 XTX trade blows in rasterized performance, so this comes down to specifics. For me, I want the XTX because itās cheaper and has more VRAM. The only reason Iād consider the 4080 would be if you are doing something specifically in Nvidiaās wheelhouse. I.e. VR use.
I donāt bother with things like frame generation because the sim is perfectly fine at lower frame rates, and the risk of artifacts when using frame generation. So while Nvidia currently scores a point there, itās not a factor that interests me.
Yes, if 4080 had 24GB VRAM it would be great !
Do you use the 7900xtx ?
Frame generation is great but it requires DX12 which is in beta in MSFS (and sometimes has odd resultsā¦) so itās something that I will not use probably
But with 16GB or 24GB the RTX4080 can provide me a smooth sim during a flight with no or few stutters (again, as smooth as it can be 
) I will be more than happy !
As long as you stay with 1440 you will be fine with 16GB VRAM.
But the truth of this Sim is VR and VR eats silicon ressources like a sperm whale eats krill.
If you plan to use triple-4K-display setup or modern VR headset (Pimax Crystal, Vario Aero) you will have resolution requirements big enough for 4090. Otherwise go for 4080 (if you can afford it easily). I assume you are not going for a competitive dog fighting, so you donāt need FPS above 40, which for me is pretty fluid.
No matter which GPU you will use the CPU load will be probably below 50%, as MSFS is unable to consume all the cores.
For MSFS, it really doesnāt matter what the averaged CPU load says. What matters is whether the specific core executing the main thread is near 100%. At that point you will get stutters, regardless of what is happening to the other cores.
How can I see the load of each core of my CPU ?
I made a test in order to ensure that for the stutters and the bad fps the GPU is the cause,
So in MSFS the default FPS counter is it changes constantly between Limited by Main Thread / Limited by GPU. In order to access each coreās usage I downloaded MSI AfterBurner, so after checking each core usage I have to say that the most high core value was 73%. In the GPU statistics the values were around 90%-97% (highest 97%).
Is the above situation GPU bottleneck ?
May a new graphics card (letās say RTX 4080) improve the situation ?
CPU: Ryzen 5 7600X
Yes, this means you are GPU-bound and a 4080 would eliminate this issue. Depending on your use case and desired FPS, even a 4070 may suffice.
It sounds like youāre borderline GPU limited, which Iāve found can induce stutters as it briefly becomes CPU limited according to the simās FPS display. If constantly cpu limited, that also makes it more prone to stutters. In other words, getting a stronger GPU and changing nothing would give you almost no FPS increase but possibly more stutters.
So now the question is what do you plan to do? Are you looking for more smoothness with the same appearance, or are you wanting to be able to crank up the graphics quality with the new card? If all you want is more smoothness with your existing frame rates, you would be better off going with one of the X3D cpuās as a first upgrade. That will keep you more GPU limited, which is generally the recommended situation. If you want to increase graphics fidelity, then a new GPU could make sense, but youāll want to tune it so that you stay GPU limited. This will necessary mean a drop in average frame rates as the trade-off for smoothness.
If you want to test this idea yourself now, turn up your graphics settings (except for TLOD and OLOD, which also hit the CPU harder) so that you are always GPU bound and see if the stutters improve. A quick way to do this is to turn the render scale up to force it to work harder. Chances are youāll have to do some re-tuning anyway with an upgrade, so at least this will get you some practice in.
If you have a free-sync monitor, check your free-sync range. For example, my monitorās free-sync range is about 43-60 Hz (max refresh). If I drop below that, Iāll start getting dropped frames and tearing, which can look like stuttering but isnāt. This will happen until I get to 30fps where itās effectively v-synced. Depending on your monitor, the stutters you see may be related to that as well. Not sure if this also applies to g-sync monitors.
I may be wrong but highest load CPU core at 73% and GPU at 97% sounds like being GPU-bound to me.
As I mention above the CPU utilization values (for each core) never goes above 73% (at my test at least, with all apps open and online (Vatsim)) for the GPU when I am inside the cockpit (without movements) it is at 90% and when moving or intense situation (weather, scenery,traffic etc) is at 97%.
Am I with the above values bottlenecked ?
Maybe I am, but trying to find benchmarks for my processor ( 5 7600X) I found a video comparing two processors and the Ryzen 5 7600X with an 3080 managed to produce 60-75 FPS and without any significant stutter at higher resolution (https://www.youtube.com/watch?v=LgbHFGN0Lkk)
Maybe this is because he is in VFR and without an complex airliner but the CPU doesnāt seem to bottleneck the GPU,maybe at the end of the video.
Also I found I review of my CPU and seems that it is able to produce around 66.7 FPS
I would appreciate an answer, if I am indeed CPU bound and buying a new GPU wonāt help, maybe I should go for a better CPU. The fact is that when I upgraded to AM5 I found this CPU pretty good for MSFS, this is why I pulled the trigger initially !
This is why I made the comment I did about being borderline. Even if single core usage isnāt at 100%, the sim is telling you that itās doing about the best it can on the CPU side of things. Maybe the bottleneck is something else, like slow RAM or poor configuration, that is hindering things, but I would trust the sim in this test over something like Afterburner.
As for what your CPU can do and what youāre seeing in reviews, that primarily comes down to tuning the settings. If you want to see what yours can do, turn your render resolution as low as possible and dial down other graphics settings. This takes all the load off the GPU so you can get everything you can from the CPU and find out what your specific setup is capable of.
Something else I just remembered regarding stuttersā¦ If you are running Razorās RGB software, that causes major stutters for me even without becoming resource bound. So donāt rule out conflicts with other software and consider shutting down anything not necessary. Iāve since switched to Signal for my RGB controls and it doesnāt cause those stutters.
I swear, this sim is more a benchmarking tool than anything sometimes. Lol
If you still decide for the 7900XTX eventually, let us know how it works for you. Iām you in the same boatā¦ the AMD vs. 4080. Those cards are in the price range I am willing to pay.
I am planning to buy a new pc. CPU is 7800x3d and GPU RTX 4090. My plan is upgrade my current 1080p TV for 4k later but before this TV upgrade, could RTX 4090 cause stutter in 1080p? If I increase render scale to 400, keep resolution 1080p, and set fps limit to 60Hz, could this help in this issue? Anyone has experience about using RTX 4090 in 1080p?
So everyone after some days of thinking itās time for my final decision!
First of all, I would like to thank each of you for your wonderful support, it helped me a lot !
Now to our topic,
I decided to go for the 4080 (Gigabyte AERO) and the Ryzen 9 7900X (maybe I should go for the 9 7900X3D) Also I saw some British Avgeek videos with great performance with the same CPU and an 4090 (but he is in 4K and I am in 2K).
Of course, the budget was exceeded with tremendous success
When the PC is back from the PC specialist, I will report you my results !
Thanks !!
Nice, Iām sure you will enjoy the upgrade!
If your primary usage is gaming - the X3D chip is probably the better choice, otherwise the non-X3D CPU will be fine as an all-rounder.