So DirectX 12 is supposed to be coming to Flight Simulator 2020 this summer at the same time MSFS is released for Xbox.
It's been said by authoritative members of this forum that the huge amount of graphic data in MSFS, compared to games, could overwhelm GPUs with insufficient memory. With that in mind, will DirectX 12 require more VRAM than DX 11 -- i.e., at that point, will the AMD RX 6000 GPUs with 16GB of memory suddenly acquire a performance advantage over the Nvidia RTX 3080 with only 10Gb in MSFS? 
Right now, neither has a significant advantage over the other, but will a Radeon RX 6800 XT be a better MSFS GPU than an RTX 3080 after the sim is ported to DX12? Or would the 3080's much higher memory bandwidth and DLSS allow it to do better under DX12.

(These questions assume that raytracing is not utilized. Just wondering about rasterization here.)

The game on the Xbox will be optimized for AMD hardware, maybe that's something to consider, but I will wait for the 20mb 3080Ti before I decide if I will upgrade.

1 hour ago, Ixoye said:

The game on the Xbox will be optimized for AMD hardware, maybe that's something to consider, but I will wait for the 20mb 3080Ti before I decide if I will upgrade.

On the other hand, Asobo said that we will have ray tracing in the future so at that point nVidia will have the advantage.

To OP I would suggest to wait: nobody knows how it will be in the future, it's better to buy after having read reviews.

Radeon RX 6800 XT performs half as good compared to RTX 3080 in Vulkan Ray Tracing tests (guru3d.com)

I hope DX12 in MSFS will be a different than P3D, On YouTube you can see cyberpunk running at 4K and even 8k and what a different DLSS can make, IMO P3D 5 was rushed and I hope when it comes to MS and Asobo using DX12 with MSFS we will see all the benefits will little down sides, frankly I think MSFS lighting looks far better than DX12 P3D, if you showed people both sim’s And asked what one has the better lighting and looks who would think P3D is running the new engine?

Edited December 19, 20205 yr by Nyxx

Asobo's MSFS game engine (by turn 10 - FtechX) was written by a subsidiary of Microsoft with direct involvement from the people that wrote DirectX, and they had Nvidia and AMD engineers involved to a lesser degree. Asobo may have tweaked it some, but it was mainly written by MS as far as I know. It's going to be difficult for anyone to replicate that level of ingrained engineering in the lighting, but the tech is becoming somewhat more encapsulated so that eventually some of the other smaller developers might have a chance at replicating the high-realism lighting and other features.

Asobo have more graphics people than low-level programmers (they have a few), but just heavier on the graphics, and this is probably why the sim has some issues. 

Here is the office where the original MSFS engine was initially created:

https://officesnapshots.com/2018/02/05/turn-10-studios-microsoft-studios-offices-redmond/#:~:text=Industry Technology%2C,critically acclaimed Forza Motorsport franchise.

 

Edited December 19, 20205 yr by Alpine Scenery

There are only ~5 major games using ray tracing right now.  Even some of the games nVIDIA touted at launch as having RT in the future still don't have it now, 2 years later.  The performance hit is so much even on the 30xx cards that you have to use DLSS to render at a lower resolution and upscale.  No matter how much nVIDIA pushes it, it's still more of a gimmick then an actual game changing feature.  (The tensor cores that they use to do RT are used for compute applications on the datacenter versions of the cards, where it makes a much bigger difference in performance)

I think the extra VRAM is probably worth more in the long run for a sim like MSFS, as the terrain mesh, ground textures, scenery, etc all get more detailed and take up more VRAM.

The 3080 Ti may be delayed into later next year, and I'm sure nVIDIA will charge out the wazoo for the privlidge of having 20GB on on of their GPUs.  Where as AMD is giving 16GB all down the stack.

10 minutes ago, marsman2020 said:

I think the extra VRAM is probably worth more in the long run for a sim like MSFS, as the terrain mesh, ground textures, scenery, etc all get more detailed and take up more VRAM.

The 3080 Ti may be delayed into later next year, and I'm sure nVIDIA will charge out the wazoo for the privlidge of having 20GB on on of their GPUs.  Where as AMD is giving 16GB all down the stack.

Could be, just hard to say where the bottleneck is on a given system given how fast the VRAM can be flushed out and reloaded these days on these newer cards. 

It's a shame of all the hardware backlogs with AMD CPU's and NVIDIA GPU's...

Edited December 19, 20205 yr by Alpine Scenery

1. The DirectX 12 implementation should not inherently require more VRAM unless you turn up the new visual features that will come with it, it just means that you cannot go over the VRAM budget anymore. However it is expected that the game will handle such a case in a better way compared to Prepar3D v5 which just shuts down when that happens, for example reducing level of detail or turning down texture quality on the fly.

2. The RX 6800 XT has similar effective memory bandwidth with the RTX 3080 due to the Infinity Cache, despite the shorter bus width and slower memory. There is a very small deficit at 4K resolution, but otherwise they're pretty much the same.

3. The ray-tracing implementation in RDNA 2 is not necessarily weaker compared to Ampere. It processes ray-triangle intersections at half the speed, but ray-box intersections at double the speed. It's just that all games until now have been optimised with NVIDIA's implementation in mind. The simulator's ray-tracing implementation will be optimised for the Xbox Series X, which means it could favour AMD hardware.

Unless you desperately need a new graphics card now, I would recommend waiting until the DirectX 12 update and relevant benchmarks are out, and hopefully the situation with the supply will be fixed by then. Otherwise, the RTX 3080 will give you superior performance now, but this could change once the DirectX 11 overhead is removed.

I've always had a horrible gut feeling that MSFS is based on the old Engine - if that is the case then we will always have performance optimisation issues going forward.

Hopefully though DX12 will help a bit more than what Asobo have said, but I'm clutching at straws there really.

Yesterday I installed a RTX 3090 in to my Ryzen 3900x build and moved my 1440p Graphics pre set to Ultra - my worst fears were confirmed, I'm massively thread limited.....

I've just left EGGD heading to EGMC - running Ultra, RAM about 27MB, CPU 15 to 21%, GPU RAM up to 10GB, GPU temp 53c, 43% usage - 33-35fps with dips into the 20s.

it's not my system, I've running benchmarks on popular AAA titles, Like Rise of the tomb raider, BF5 and Red dead - fps are as expected.

 

12 minutes ago, hanhamreds said:

I've always had a horrible gut feeling that MSFS is based on the old Engine - if that is the case then we will always have performance optimisation issues going forward.

Hopefully though DX12 will help a bit more than what Asobo have said, but I'm clutching at straws there really.

Yesterday I installed a RTX 3090 in to my Ryzen 3900x build and moved my 1440p Graphics pre set to Ultra - my worst fears were confirmed, I'm massively thread limited.....

I've just left EGGD heading to EGMC - running Ultra, RAM about 27MB, CPU 15 to 21%, GPU RAM up to 10GB, GPU temp 53c, 43% usage - 33-35fps with dips into the 20s.

it's not my system, I've running benchmarks on popular AAA titles, Like Rise of the tomb raider, BF5 and Red dead - fps are as expected.

 

The rendering engine isn't based on FSX or P3D legacy code if that is what you mean, it's definitely based on the same engine as Forza. The original alpha design of MSFS was the Ftech X engine. It has now been modded so much that I hesitate to still call it the FTECH engine, as it is now a frankenstein version of Ftech X, but I don't think they officially ever renamed the engine. I would just say it is now its own engine, but shares 90%+ of the same code as FtechX from Forza.

There is legacy code from FSX, but it's not in the rendering, all the legacy code is from other stuff and XML junk and what not. I'm not saying a couple stray graphics API''s may or may not have accidentally or intentionally been ported in from FSX, but it is definitely not using that engine to do the rendering, it is definitely using a modded Ftech X. This isn't speculation, it's known as 100% certain.

https://www.sportsgaming.win/2020/10/microsoft-flight-simulator-graphics-are.html

In the interview the CEO confirms that FTech Engine was “slightly modified to support a large data load “. He also specified that "all the 3D textures and data used come from the FTech Engine in cooperation with Azure".

 

Edited December 19, 20205 yr by Alpine Scenery

1 hour ago, hanhamreds said:

Hopefully though DX12 will help a bit more than what Asobo have said, but I'm clutching at straws there really.

They did say it will benefit people with the older / less powerful CPU's the most. 🙂👍

1 hour ago, ChaoticBeauty said:

 

2. The RX 6800 XT has similar effective memory bandwidth with the RTX 3080 due to the Infinity Cache, despite the shorter bus width and slower memory. There is a very small deficit at 4K resolution, but otherwise they're pretty much the same.

 

 I recently had a bit of a debate with a colleague at work between the 3080 v 6800XT and the amount Vram on the said cards. As I now have a 4k monitor I was telling him that I plan to get a 6800xt rather than a 3080, he was insistent that effectively they have about the same amount of Vram because of the way the GDDR6x handles the memory better than plain old GDDR6 on the AMD card. I basically said the same as you on the bandwidth but that to prevent future possible OOM's etc the AMD card with 16GB is better for 4k rather the 10GB 3080 in this instance. He was adamant that he was right and that I was wrong, we just agreed to disagree. Surely I'm right, what's your opinion?

Definitely I don't think the implementation of DX12 in MSFS will be similar to P3D, MSFS is an AAA title and Asobo have the experience to optimize it, don't forget they need this optimizations for XBox serious X/S. Also I wouldnt be surprised if in the sim you can choose which DX version you want to run, I have seen that common in few games.

1 hour ago, hanhamreds said:

I've always had a horrible gut feeling that MSFS is based on the old Engine - if that is the case then we will always have performance optimisation issues going forward.

Hopefully though DX12 will help a bit more than what Asobo have said, but I'm clutching at straws there really.

Yesterday I installed a RTX 3090 in to my Ryzen 3900x build and moved my 1440p Graphics pre set to Ultra - my worst fears were confirmed, I'm massively thread limited.....

I've just left EGGD heading to EGMC - running Ultra, RAM about 27MB, CPU 15 to 21%, GPU RAM up to 10GB, GPU temp 53c, 43% usage - 33-35fps with dips into the 20s.

it's not my system, I've running benchmarks on popular AAA titles, Like Rise of the tomb raider, BF5 and Red dead - fps are as expected.

 

What's your other settings, have you got things like FPS capped?

If so it might be holding your system back.