CPU gets really hot when rendering with the GPU

[Mokiki]

This is more of an odd issue that I recently noticed when trying to render on my gpu with vray 5 Update 2.1
Normally when rendering on my CPU the temps don't really go above 70 degrees Celsius. When I render on the GPU the cpu temp goes to 90 and stays there consistently. While the GPU hovers around 55 Celsius.
Though if I have another window like my browser in the front and have 3ds max in the background the CPU temp drops to 79 and then goes back to 90 when I focus on 3ds max again.

This seems weirdly strange since the CPU shouldn't be taxed that much.

Configuration:
Windows 11
CPU: Ryzen 5950x
GPU: RTX 3090 FE (Studio Ready Drivers 472.47)|
Vray version: Vray 5 Update 2.1
3ds max 2022.2

Anybody knows what might be the problem here?

[Muhammed_Hamed]

Normally when rendering on my CPU the temps don't really go above 70 degrees Celsius. When I render on the GPU the cpu temp goes to 90 and stays there consistently. While the GPU hovers around 55 Celsius.

Hi Mokiki

This behavior is normal, I do experience this on my 5950X as well. 90 degrees is fine for this CPU in AMD's words
What happens is that the CPU uses higher voltage and boosts higher with some specific workloads, specially things that don't push all cores(the new Ryzen CPUs are cooler on all-core loads somehow)
If you want to disable this go to bios, and make sure PBO is disabled

Best,
Muhammed

[Mokiki]

Thank you for the response. I guess my main confusion comes from why the cpu is taxed during gpu rendering. Especially different depending on whether 3ds max is in the foreground or not.
Probably it's cooler during all core workloads since it doesn't boost that high and the heat is spread across the whole cpu instead of just small parts so the cpu cooler can do a better job.

[Muhammed_Hamed]

I guess my main confusion comes from why the cpu is taxed during gpu rendering. Especially different depending on whether 3ds max is in the foreground or not.

V-Ray GPU uses a lot of CPU resources specially with a high end GPU like a 3090, Progressive mode should be a bit better on that. But still it will push your CPU on 6 or 8 cores
It is something we plan to address in the new future.

Best,
Muhammed

[Mokiki]

Good to know! Once again thank you for the clarification
Even though gpu rendering has been available for a while I only recently started to make more use of it. Since it's just so much faster.
Sadly the forest color map isn't working on GPU which I make use of quite often but so far for a lot of other cases GPU rendering has been a timer saver and I am excited to see how things progress.

[Muhammed_Hamed]

Sadly the forest color map isn't working on GPU which I make use of quite often

It should work fine, what V-Ray version are you using?
This might be something specific to your setup, If you get me a simple scene showing the issue, I will make sure this is fixed

Best
Muhammed

[Mokiki]

It should work fine, what V-Ray version are you using?
This might be something specific to your setup, If you get me a simple scene showing the issue, I will make sure this is fixed

Best
Muhammed

I am using the newest version on the homepage. When using the tint option with "as map on surface" it doesn't work.

CPU Result:


GPU Result:


Shader Setup:

[Martin.Minev]

Hi Mokiki,

The Forest Color tint mapped by a texture is not supported currently. We have it reported to our bug-tracker (VMAX-7629) and we will increase the priority.
Could you please send us the scene file here, so we can add it to our report and make sure your case will be supported. We will notify you when there is an update.

Thanks!

[Mokiki]

Martin.Minev
Thank you for getting back to me. I sent out a ticket (Ticket Number: 16220) with the 3ds max (2022) file.
Hope this helps!

[matanov]

Fixed in the latest release.