Unreal Engine Path Tracing not working on B series

[Miguel1900]

Hi Intel,

I'm glad I have discovered this forum, where I found a similar issue (https://community.intel.com/t5/Developing-Games-on-Intel/Arc-a770-path-tracing-does-not-display-in-Unreal-Engine/m-p/1627059) (still not solved?) and where you even mentioned reporting the issue to the engineers. So useful.

Well, I have a very similar issue to that one. I have developed a benchmark based on UE5.5 and it seems Intel Arc GPUs can execute the builtin path tracing test included. Some A series have been able to execute it (A580 and A770), other fail. But any B series is able to finish the test. As reported by many users (https://www.reddit.com/r/IntelArc/comments/1jaqy85/please_run_your_arc_in_my_benchmark_i_need_more/), they won't see anything when rendering, just a black screen, so the test can't continue because im fact Unreal is rendering nothing, so it doesn't detect any progress.

Please, the best thing is that you test it yourself: install GameTechBench from Steam. You will need the 'Pro' DLC to unlock the Path Tracing test inside the benchmark. Once you have it, just select that benchmark mode and press play. Please, keep me informed even when you are just starting to test the benchmark, even if you still don't have any reply, but to know you are on it.

This is the same Path Tracing rendering as when you render a sequence from the Unreal editor.

I'm really awaiting your reply. Please, I don't want to tell Intel users their GPUs are not compatible with the PT test nor the Unreal PT, in general.

Thank you very much and best regards,
Miguel

[karen_intel]

Hey @Miguel1900 thanks for reaching out

About the other thread you mention, still not solved. We were waiting for the project to do some research and report to the driver team and the submitter didn't get back to us

BTW, Update on your request:
I purchased the DLC version and ran the Benchmark with my B580 driver v.6647
Ray tracing: Ran fine, score of 1191
Path tracing: It runs as the audio is still going but there is grain everywhere and doesn't run as smoothly as in Ray Tracing
It ended ok, score of 346. It didn't crash for me but I see a lot of noise
Do you have a video of how is it supposed to look?

Appreciate your patience and help in advance

Karen

[Miguel1900]

Hi @karen_intel !

Thank you for replying!

Not sure if being happy or sad because you passed the test. Even if you had that "luck", reading the Reddit thread you will find many B580 users having the "black screen" issue. And most users in that thread had a B580; I would say the 90-95% of them failed to pass it. Any other GPU users reported it. Even more: if you look in my leaderboards, many B580 were over there (33 just in RT 1080p!) and only 2 B580 users (one should be you, I suppose) were able to run the PT test. Additionally, some A770 users passed it, even if most users had a B580. And the B580 gets a lower score than the A770 or other A series of even a lower tier.

Anyway, I think you probably ran the test succesfully, if you arrived until the summary screen. This is an old video, but it shows how it works: warming phases are super noisy, until it starts rendering each image, cleaning the noise iterativelly during a given time. As the scores are very low (due to GPU performance), they probably won't be able to clear a lot of the noise before the countdown finishes: https://www.youtube.com/watch?v=DqTuVqgRKu8

Thank you very much for keeping an eye!

[karen_intel]

@Miguel1900 hello again

Yeah I was kind of surprised too when it ended even tho the noise and perf is too slow in my B580.

Something you can tell the users (that makes a difference at times) is to disable their iGPU and install the driver after having cleaned the previous one with DDU, wondering if that would help with the black screen/crash.

About the test I made, I can see there are some differences with what I'm seeing vs your video so, we can definitely follow the Path tracing performance differences and report it internally using your Benchmark.

I need to do some testing in other machines to gather more data and see what the dev team needs.

I'll get back to you next week with the report ID so, talk to you soon

Karen

[Miguel1900]

Thank you for your reply, @karen_intel!

I’ve recorded a video showing the current (and final) state of the PathTracing test so you can check if you still see any differences compared to my video: https://youtu.be/f8GUp2ZOGjs

To ensure an accurate comparison, you should match both videos at the same progress point (for example, comparing the moment when you reach 100 rendered samples vs my same rendered sample count, approx.).

By the way, I also have an user testing it on a B580, and he mentioned he can only run it with the Low VRAM mode enabled. Is that the case for you as well?

Thank you again for looking into this! Intel users are lucky to have your active support.

Looking forward your the next insights!

[karen_intel]

Hey @Miguel1900 
Thanks for the video! It is very helpful for my debug!

About the Low VRAM Mode Enabled: yes, I can confirm it works for me only if it is set in ON.

Otherwise, it keeps warming up, the music going on but the benchmark never starts.

Thanks a lot for your comments. Deeply appreciated, glad we can make a difference

I'll keep you posted on my internal report. Got a few cases on queue so, stay tuned

Karen