So I put a new AMD 5800X3D in my PC and then had some issues leading to a clean re-install of Win 10 and also a total clean re-install of MSFS2020. I made the mistake of choosing my D: drive for the initial download path from Xbox app but it seemed to load OK and I continued with the rest of the install to my D: drive (a M.2 SSD) and everything went smoothly. Proceeded with all the updates and bought an aircraft from the marketplace (Beech Staggerwing) then set all my General and Control options as before.
MSFS started just fine and so far flies and works great @ 82fps (RTX 3080) mostly high graphics, etc.
Now here’s the quandary: I was under the impression that MSFS 2020 required the base system stuff to be located on the C: drive with windows and that you could place your packages install and Community stuff on any drive that had room for it and that the sim would not work if the primary folders were not placed on the C: drive. So why does my install run just fine ALL from the D: drive? I cannot find any MSFS 2020 files or folders at all on the C: drive like the first time I installed the sim. Is this weird?
I didn’t think you could do that either, but I’m sure everyone has their own story and experience with paths. I tried my best to prevent anything from being loaded on my C: drive with Windows, but anytime I reinstalled, it still created an AppData\Roaming\Microsoft Flight Simulator directory (I’m a Steam user).
Everything has worked fine, and it was only like 57 meg, so I didn’t worry too much about it. But I admit I will be curious as to what happens the next time MSFS updates your system. I hope you get to keep it the way it is and that it continues to work for you.
I’ve tried both ways. I found no noticeable difference, improvement or loss.
My intial install was like yours, everything on D.
( or any other drive you chose ). Over a year like that with zero issues with updates, purchases or performance.
In a way, maybe easier to find files maybe. Store version.
Yes, I wonder what will happen on the next update too. Guess I will just have to wait and see when it arrives, but it will be of interest when it does.
Unless you again change the programs install path in steam or store it should be no different to the default C:
However I will always recommend keeping the package files away from your system drive, 99% of the time you would not notice but why take the chance of Windows freezing just as you’re about to land that VIP flight? I also remove the page file from the package drive for the same reason, so as long as you have one elsewhere it’s OK.
You can install the sim anywhere you like, just like any other program. But Microsoft recommend C: and that’s good enough for me; I reckon they must know a thing or two about Windows programs.
The packages, as everyone knows, are another matter. And they’re easy to move if you change your mind.
I’ve a Steam version myself and I simlinked/junctioned all the C: folders pertaining to MSFS to the partition that my game install uses
I rather think that if Windows froze, no matter what drive it was on and what drive your game was on, then your game is lost. The system ultimately controls all of the writing to drives, networking, etc.
What I actually mean is maybe Windows wants to access or write data to the system drive at the same time e.g. Windows update. For some this could be the difference between a single dropped frame and half a dozen … And with a little forethought for most of us it’s avoidable.
Ah, I get you. On that thought, I do remember seeing a tip that suggested turning off or inhibiting background updates (if you weren’t aware already 
)
For sure, while gaming Windows 11 does that by default, however there’s more to an OS than Windows updates and some system files still need to be accessed. Why take the chance if you really don’t need to?
Just a quick update on the latest update (I say with tongue in cheek;-): yesterday I installed the latest update 1.30.12.0 and it went smoothly with MSFS recognizing my D: path right from the start. Had zero issues and flew a short 30 minute flight in my Vans RV-14 with no problems afterwards. So my complete D: drive, a SSD M.2 gen 4 Sabrent Rocket 1 TB, install works just fine. Noting this as the big question for me was whether I was going to have issues with the updates and apparently that is nothing to worry about.