DX11 or DX12 in VR

[odourboy 1,289]

What are you all using and have you found any advantages/disadvantages of using one or the other in VR? I can't say I notice anything obvious,  but I've only tried a couple of DX12 flights to compare and I've got frames locked using the Virtual desktop SSW/Snapdragon chip frame doubling capability, so I might not see some of the differences that might be apparent to others. 

Edited May 22, 2023 by odourboy

[turbomax 3,286]

53 minutes ago, odourboy said:

Snapdragon chip frame doubling capability

sounds interesting, though I may not be able to use it with my HP G2, does it really double your frame rate in VR just like the 4090 does in 2D?

[odourboy 1,289]

26 minutes ago, turbomax said:

sounds interesting, though I may not be able to use it with my HP G2, does it really double your frame rate in VR just like the 4090 does in 2D?

Yes. And frame generation considers head tracker movement so panning is perfect! It's not all wine and roses though... it creates some in-sim motion related artifacts, and things really go south if you can't consistently hold half the refresh rate. I'm currently using a 72 fps refresh, so I'm locked at 36 in the sim. Solid and smooth 72 in the HMD. I could use 90, but I found with the settings I'm using (4412x4412 rendering resolution, real time traffic, real time weather and TLOD 200) I couldn't always hold the necessary 45 fps for SSW to work reliably. 

Anyway... what about DX11 vs DX12? Thoughts? 🤔.  

[Daube 353]

I'm still using DX11, as my old video card doesn't really benefits from the DX12 architectural changes...

Your comments regarding the 72Hz display option in the HMD are interesting though... I admit I haven't taken much time to investigate/test that mode so far. I set it to 90Hz with a kind of hope like "please go as high as you can, when you can...", something like that. Maybe that could be counter-productive in the end ?

[turbomax 3,286]

12 hours ago, odourboy said:

what about DX11 vs DX12? Thoughts?

why not simply switch back and forth in the MSFS graphics settings and check the results. no need to install anything?

DX12 is required to enable Frame generation.

"The biggest advantage that DirectX 12 brings is lower CPU overhead. DirectX 11 only uses one core on your CPU for graphics tasks like rendering. But with DirectX 12, you can use up to six cores or even more if your CPU supports Hyper-threading. 

https://windowsreport.com/directx-11-vs-12/

Because it uses less CPU time than earlier versions of DirectX, it allows your PC to run games more smoothly by handing off work from the CPU onto the GPU instead. "

https://www.digitaltrends.com/computing/directx-12-vs-directx-11/

https://www.makeuseof.com/directx-11-vs-directx-12-differences/

 

Edited May 23, 2023 by turbomax

[Reset XPDR 1,271]

I get 20% lower performance using DX12, so I use DX11.

Also, although you may see double the FPS on the VR preview window on your monitor, DLSS 3 frame generation does not work in my G2 headset and stuttering is worse.

[odourboy 1,289]

15 minutes ago, Reset XPDR said:

I get 20% lower performance using DX12, so I use DX11.

I was doing more testing this afternoon and I'm coming to the same conclusion. DX12 is less efficient and without frame generation as an option, I'm not seeing any upside over DX11.

[-Belga- 141]

On my system (AMD 5800X3D, RTX3080 (10GB), 32 GB DDR4-RAM) it's exactly the other way around. My FPS and frame times are way better when using DX12. With DX11 I'm always CPU (main thread) limited, with DX12 the overall system load is more balanced.

[joby33y 152]

Obviously, mileages vary.  I had experienced lockups / crashes with 12, but I’ve got 11 working great with OXR toolkit & Rvrb.  Super smooth VR flying…it ‘aint broke, so….

I’ll give 12 another go after it matures a bit more.  
 
But that rig you have!  It oughta handle anything you throw at it.  

[MauBen 82]

On 5/23/2023 at 9:40 PM, odourboy said:

I was doing more testing this afternoon and I'm coming to the same conclusion. DX12 is less efficient and without frame generation as an option, I'm not seeing any upside over DX11.

I had been running with no problems with DX12, but after the latest Windows 11 update which I ran yesterday, MSFS would crash every time shortly after the flight was loaded. So, just for fun, I changed to DX11 and voila, all back to normal. No idea why the latest Windows update messed up MSFS and DX12, but this is what happened. Coincidence? Maybe.

 

[Donka 645]

I've only every used DX11 in VR but tried it out today with the developer overlay for FPS and notice that I'm seeing less GPU time in DX12 while CPU and Render times are similar to DX11 so seems DX12 is working better for me. Not noticed any visual difference between the two in VR. I will need to test further this weekend though as I haven't seen any stutters at all in VR approaching an airport under DX12 but would notice micro stutters from time to time on approach under DX11.

[TheFamilyMan 280]

I've found that when doing MSFS dx11<=>dx12 swaps it's best to use Windows Disk Cleanup to clear the DirectX cache before launching MSFS after the swap.   I recall seeing less than expected results for some of times that I forgot to do this, though never a hang or CTD. 

Edited May 26, 2023 by TheFamilyMan