Vray for blender cpu faster than gpu?

[Kornpcgamer]

Hi, it is really driving me crazy how does cpu rendering is significantly faster than gpu, i dont get it.
-i use the fichycat scene provided in the download section for blender nightlies
-my system is CPU: i9 7900x and 4 freaking 1080ti's.

how can an i9 beat 4x1080ti pls i need answers otherwise i am going crazy.
Thank you

[JuhaW]

Is it using all gpu's ? Dont know if this helps but check V-Ray\Standalone for x64\bin\x64\vc14\vray_gpu_device_select.exe

[bdancer]

Seem like GPU defaults are not good enough, try setting "Ray Bundle" to 256 and "Rays Per Pixel" to 16.
I've pushed those default to tomorrows nightly.

[boyan]

Hey, Kornpcgamer,

Can you share the scene file and V-Ray settings with me? What is the build number of V-Ray for Blender? Meanwhile, for the reference point for you can use a benchmark test. V-Ray benchmark can be downloaded from here:https://download.chaosgroup.com/?product=57.
If it possible to share with me and ocldeviceselect.exe window. Press WIN+S and type ocl.. check the selected devices for GPU rendering.

Cheers,

[Kornpcgamer]

Hey, Kornpcgamer,

Can you share the scene file and V-Ray settings with me? What is the build number of V-Ray for Blender? Meanwhile, for the reference point for you can use a benchmark test. V-Ray benchmark can be downloaded from here:https://download.chaosgroup.com/?product=57.
If it possible to share with me and ocldeviceselect.exe window. Press WIN+S and type ocl.. check the selected devices for GPU rendering.

Cheers,

Hi boyan and bdancer, Thanks for trying to help i really do appreciate it.
-the build is several builds from this week. exporter version 3.2155 says in blender.
- i attached a screenshot of what you asked.
- upping the rays per pixel as bdancer told me didnt change anything in my render times.

in vray benchmark my gpus are clearly superior to the cpu thank god.

-- also after a lot of tries i think i got something. i tried a really basic cube scene with a sun and the render times are 18s in gpus and 7 secs in cpu but then i got the idea it may be the export time that is making the difference so did animate the cube and rendered the animation and only then the first frame was 18 secs and all other frames did 7 to 9 sec/frame in gpus and cpu kept its concistancy of 7 secs a frame. but i was still hoping that 4 gpus can do 2 to 4 sec per frame concidering the simplicity of the scene and then it struck me. may be in more complexe scenes gpus will stretch legs so i downloaded a scene provided by bdancer. and render times are 29sec for gpus(including export additional time) and 42 sec in cpu as showed in the screenshot. i still expect more performance from these cards and vray. i am still begginer with vray so may be i dont know how to proper set it yet to optimize gpu perf.

Anyway if you could guide more into some gpu rendering stuff (i am reading all the available documentation and some max tutorials).

also a vray device select says gtx 1080ti cuda 6.1 isnt that outdated or an issue??

Huge thank you for answering. cheers

[boyan]

Hey, Kornpcgamer,

Thank you for the feedback and details. I think the first delay might be because of the kernel build when you're using GPU for the first time or when the driver is updated. You can decrease the render time by simply increasing the threshold. Btw, by default CPU Progressive used threshold - 0.01 and GPU 0.008 if you want to compare them make it equal.

Cheers,

[a7az0th]

Hi Kornpcgamer,

The line in GPU Device Selector that says CUDA 6.1 is a bit misleading. It doesn't show the CUDA version , but the Compute Capability of your GPU and for a GTX 1080TI this is 6.1.
Apart from that, 4x1080 should be quite fast. Could you share the scene you are working on and having issues with so we can check it out and maybe guide you in setting it up properly so you can take full advantage of the performance your GPUs can give you?

Best,
Alexander