VRay RT GPU not using both GPUs - only one

[padre.ayuso]

I have checked the VRay Render Devices Select and both my GPU GTX 970 are selected. When I check the usage for both of my GPUs only one is being used, I use Tech PowerUp GPU-Z to check this out. Under GPU Load, one is at 100% and the other is at 0%. Is there something else I need to check? I have also noticed that my renderings take the same time or longer when I have both checked, which means that I'm not using both. Previously I was going to buy an SLI connector, but I was told that this was useless.

Should I also check my mother board? It is 8 years old and while I'm in the process of getting a new computer with newer specs, I don't want to run into this in the future. Another thing that I have noticed is that my NVidia Control, I have checked the control for PhysX at the recommended setting which is for the computer to work it out, (Automatic). Should I change this?

As additional data, it seems to work fine now that I have stripped quite a few complicated materials I had. Wish I could tell you what the problem was exactly, but needless to say, it works but it took quite a bit of trial and error and I seem to not always have this fully working for every scene. Any pointers?

[svetlozar.draganov]

What V-Ray/3dsMax version you are using?
Which Device Selector you are using, in the latest versions the Device Selector is available in the Render Settings UI but it is also available as a separate tool under the Start Menu > Chaosgroup > V-Ray RT folder:


Does the VRAY_OPENLC_PLATFORMS_x64 environment variable exists in System or User Environment Variables?
Does the issue appear on both OpenCL and Cuda engine?

Please use the Nvidia GPU Utilization tool which comes with the drivers:
C:\Program Files\NVIDIA Corporation\Control Panel Client\NvGpuUtilization.exe

[padre.ayuso]

What V-Ray/3dsMax version you are using?
Which Device Selector you are using, in the latest versions the Device Selector is available in the Render Settings UI but it is also available as a separate tool under the Start Menu > Chaosgroup > V-Ray RT folder:
[ATTACH=CONFIG]29469[/ATTACH]

Does the VRAY_OPENLC_PLATFORMS_x64 environment variable exists in System or User Environment Variables?
Does the issue appear on both OpenCL and Cuda engine?

Please use the Nvidia GPU Utilization tool which comes with the drivers:
C:\Program Files\NVIDIA Corporation\Control Panel Client\NvGpuUtilization.exe
[ATTACH=CONFIG]29470[/ATTACH]

Thanks. It seems to work fine now not sure what had happened on my previous scenes. I'll be testing DR with VRay RT GPU afterwards, unless you think I should make it a public concern and put it on the forum, I'll write to you afterwards if I have some issues, which I had about two months ago.

[padre.ayuso]

One other question, if I send a rendering with Backburner for VRay RT CPU and I ask to render with both GPUs only one gets used. Is there something to set up? I have tried setting it up on the workstation and then sending it to the slave machine and it seems the information is not retained there. And then I also checked the box from the tool provided by Chaos to turn on both GPUs. Please advice.

Thank you.

[vlado]

If you look at the V-Ray log file, does it say that it uses just one GPU?

Best regards,
Vlado

[padre.ayuso]

Can you refresh my memory on how to get the Log File? :S

Then I'll test it in the morning.

Alex

[yavor.rubenov]

Hello,

The V-Ray log file from 3ds Max is located in the temp folder of the current user (%temp% in windows explorer) and is named vraylog.txt

Best regards,
Yavor

[padre.ayuso]

Hey Vlado,

Sorry to get back to you this late. In one computer both GPUs are working full blast (same scene) when sent on backburner. The other computer, when sent on backburner is only using one GPU. I'll be sending you the VRay log file shortly via email.

Alex

[svetlozar.draganov]

Thank you very much for the log file, the render indeed happen only on one GPU device.
Let's ensure that V-Ray is set up to use all the GPU devices for the rendering.

For the purpose please log on remotely on each machine open OpenCL Device Selector as administrator:
C:\Program Files\Chaos Group\V-Ray\RT for 3ds Max 2016 for x64\bin\ocldeviceselect.exe

Make sure that all the GPU devices are selected, hit the Set Devices button and check the Output message windows that everything was set correctly (no fail messages).