Low FPS on Rendering with DX12

Development Rendering
1

Hello together,

When I execute the archviz interior rendering project setup and open it in UE4 I have constant 7FPS!
I have a six-core computer 4.0 GHZ(32 GB RAM) and a NVIDIA 1080 with 8 GB memory.
Why does the FPS rate break down so much, that you can’t do anything anymore?
This is this project:

[https://www.unrealengine.com/en-US/b…-now-available

When i switch over to DX11 the frames run smooth by 60 FPS but the bottleneck is DX 12, there i have only 7 FPS.
My System can handle Dx12, cause the Diagnostic says DX 12.

What do i do wrong?](New Archviz Interior Rendering sample project now available! - Unreal Engine)

Thanks a lot for a solution!

2

when you use DX12 the ray tracing is used but not with DX11

3

Hello Julian Thanks a lot for your answer, what can i do to have the same FPs like on Dx11. I mean the card GTX 1080 can handle DX12 Data.

4

By the Way DX11 and DX12 support Raytracing…this is also viewable under the Project Settings->Render->Raytrace on or off
Microsoft says that DX11 has also the capabilty for Raytracing!

5

True oddly never thought about it, but ARE there differences, does DX12 do it better or faster under some circumstances?
https://www.dsogaming.com/news/dx11-…ing-tech-demo/

ForDX12 " In the case of hitting the fallback layer, DXR will be executed via DirectCompute compute shaders, which are already supported on all DX12 GPUs. >https://www.anandtech.com/show/12547…ctx-raytracing

HM, so a GTX 950 which has served me VERY well, can do raytracing now, albeit slower . Indeed it can, as I tried it once and everything looked like what one would expect but FPS suffered so I turned it off, but I was using 4.24.1 I believe which for many here has severe fps problems.

But does Dx11 have api to address raytracing given I’ve so far only been able to find it for DX12?
https://archive.techarp.com/showarti…tno=526&pgno=1, looks like RT was just in initial stages ?

Dunno, I’ve never followed such things until this year , anyone else can verify - IE: did DX11 EVER have a API for it and who use ready to use it ?

6

If you’re going to use ray-tracing then it’s going to be slow, the GTX 1080 technically has support for it but isn’t optimized for it at all (it would need dedicated ray-tracing cores) so it’s not going to perform well that way. Unless you need a DX12 feature, then use DX11

7

Thank you Dartviper107
This has solved my issue i think i have to invest in an RTX 2070/2080 GraphicCard

8

I have the same issue with DX12 and my GTX 1080 but it’s not limited to Unreal. I experience the issue in all games. For some reason with DX12 the GPU utilization averages between 3 and 12%, but if I switch to DX11 my utilization jumps to 70 -90%.
I don’t know if the problem is with the GPU or the renderer. I read somewhere that DX12 also has issues with a high core count and low base clock which is my case. I have an i9-7920X which has a core clock of 2.9ghz with Turbo up to 4.0ghz, and 12 cores/24 threads.
I’m curious what is your specific processor?