Ryzen 9950X3D: Thread #17 Not Used When 3ds Max 2025–2026 is Open

[cgirenderhome]

Hi there,

One week ago I switched from a Ryzen 9950X to a Ryzen 9950X3D, and I noticed an issue related to CPU thread usage in 3ds Max 2026.

When I start a render in V-Ray, Corona, or Arnold, one logical CPU thread (out of 32 total) is not being used — it is always thread #17.

Additionally, while 3ds Max 2026 is open, external benchmarks such as Corona Benchmark 1.3 or Corona Benchmark 10 also do not use thread #17. As soon as I close 3ds Max, all 32 threads are used normally again.

Important observations:

• In 3ds Max 2023, everything works correctly — all 32 threads are fully utilized

• The issue appears only in 3ds Max 2026

• The missing thread is always the same (thread 17)

What I have already tried:

• Setting CPU affinity via Task Manager and Process Lasso

• Different BIOS versions and BIOS settings (including default)

• Clean Windows installation

• Latest chipset drivers and GPU drivers

None of these steps resolved the issue.

This looks like a CPU affinity / thread scheduling regression introduced in 3ds Max 2026, possibly related to changes in the internal thread manager or CPU pinning logic.

If anyone has experienced a similar issue or has a workaround, I would really appreciate your help.

Best regards,

[heather_tracy]

Hi @cgirenderhome,

I wanted to check in and see if you still needed assistance, or if you found a solution to your question already? Let us know if you need further assistance by providing an update or if you have found a solution, please share it with the community so other members who may have the same question could learn from your experience.

All the best,

Heather | Community Manager

[cgirenderhome]

Hi Heather, nope, I didn't find any solution and need assistance, thats why I posted here the question 🙂

[MartinBeh]

That is an odd issue indeed.

What happens if you use the Scanline renderer (just for a test) - does that use all cores?

And is there anything in 3ds Max you can do to make thread 17 do some real work, for example a lot of UI/viewport changes?

[cgirenderhome]

Hi Martin,

Thanks for taking a look into my problem. Nope, Scanline, V-Ray, or Corona—everything shows the same issue. It looks like a 3ds Max problem, because the 2023 version works perfectly.

The funny thing is that if 3ds Max is open, the benchmark also doesn’t use the 17th CPU thread. I once tried, with the help of ChatGPT, to change some Windows variables, something like
ADSK_3DSMAX_DISABLE_PERFORMANCE_LAYER=1.
With an empty 3ds Max scene and Corona Renderer, all threads were used, but after opening a scene, thread 17 was no longer used. And after It`s no longer used 17 thread.

So I don’t really know what to do, and I would appreciate any help!

[MartinBeh]

No idea what is going on. What happens to your thread #17 if you do some interactive work, for example a lot of UI/viewport changes?

And what happens if you turn off multithreading in the BIOS, so you end up with 16 cores? Will they all be used or is one also idle?

It is weird - but loosing one thread out of 32 equals a 3% performance loss. I would not pull too much hair out about this.

[cgirenderhome]

When I’m doing interactive work, thread 17 isn’t used. As I said, if 3ds Max is open, thread 17 is basically dead.
I also tried disabling SMT as you mentioned, and then core 0 wasn’t used either. It really looks like a 3ds Max 2026 bug. I understand it’s only around a 3% performance loss, but still — this is clearly a 3ds Max bug, and it shouldn’t be happening. If someone buys a high‑end CPU and ends up with this kind of issue, it’s just not okay.
Anyway, thanks for helping!

[MartinBeh]

I am trying to contact some developer on this.

[cgirenderhome]

That`s will be great! Thanks you for you help!

[logan_foster_adsk]

Out of curiosity what is the priority of the application set to if you were to look at it in Task Manager?

[cgirenderhome]

The priority is set to normal, but also tried low, high and no changes.

[lauri_barnhart]

Hi @cgirenderhome,

I wanted to check in and see if you still needed assistance, or if you found a solution to your question already? Let us know if you need further assistance by providing an update or if you have found a solution, please share it with the community so other members who may have the same question could learn from your experience.

All the best,

Lauri | Community Manager

[cgirenderhome]

Hello, I need an assistance of course. The Problem is still persist!

[haifeng_yuSEVKN]

hello @cgirenderhome, thank you very much for your post. Please allow me some time to consult with our team to see if there is more information I can share with you. Thank you!

[haifeng_yuSEVKN]

Hello @cgirenderhome, If this option is available to you. Is it possible to test turning hyper threading off and see if there is still a core not being used? Thank you.

[cgirenderhome]

Hello Haifeng, thanks for answer. I tried and the one core is not using.

[haifeng_yuSEVKN]

Hello @cgirenderhome, thank you very much for the information. If I understand correctly, even turning off hyper threading, and only thread 17 was used. Is that correct?

Also, if it's possible, could you try changing the display driver to see how it goes? You can change the settings from Customize> Preference Settings > Display Driver > Choose Driver (Legacy OpenGL), then close and reopen 3ds Max. Thank you!

[navya_gelli]

Hi @cgirenderhome ,

Did the info from @haifeng_yuSEVKN help answer your question?

If it did, it’d be great if you could click the "Accept Solution" button so others can easily find it too.

If you’re still needing more help, feel free to share an update here. The community will be happy to jump in with any next steps to help you get where you need to be.

Best, 

Navya | Community Manager

[cgirenderhome]

Sorry that I was some time offline, have a lot of work... If I turning off hyper threading, the core where the thread 17 was (9 core) also not working (dead). I tried also, as you mentioned, to change the driver in to Legacy OpenGL, but after changing no big news, the thread 17 still not working.... Do you have some more Ideas?

[cgirenderhome]

I still need an assistance, the problem still persist. Sorry, for a long offline.