Need help with gpu failing to render iray.

mid_knight

I can't figure out what the deal is.  I have a 2x gtx 1080 cards. 8GB vram each.  I loaded up a scene that has a structure, skymap, one genesis 8 character, that's only half dressed and a hair model.   For the life of me I can't get this thing to render out on the GPU's.  It keeps reverting back to CPU.  This is hardly a complex scene and it rendered a few months ago just fine. 

Charlotte 8

AxarraHeadress

Relentless Mercinary Corset

OnFleek Eyebrows

Ruins - The First snow

and an Iray Worlds Skydome/sun light

 

fastbike1

First, how do you know it's not rendering on GPU. If you are looking in Program Manager, the default settings won't show GPU usage. GPU-z is a much better monitor.

Second, if usin Windows 10, has a Windows update overwriiten you Nvidia driver?

Third, what version of Studio are you using? Studio 4.12 prodcution version and the Studio 4.12 Beta have minimum Nvidia driver versions. Drvier 430.86 has been reliable on cards from the 900 series to the RTX cards.

mid_knight

I know it's not using my GPU because it's sitting at zero CUDA utilization.  THis is verified in both afterburner and hwinfo64.  Plus it's crazy slow.  There's a clear diffence between a 12 core cpu and dual gpu rendering times.

No.. windows hasn't overwritten my display driver.  I have device driver updating disabled.  I'm currently on version 436.30

I'm using public build 4.12.0.86

 

mid_knight

Just tried the beta version.. all it does it crash.  Never renders anything.

Richard Haseltine

Have you tried a scene consisting of a single primitive?

mid_knight

yes.. a single primative cube renders on both GPU's just fine

Is there a way to find out how much vram a scene requires before hitting render? or after even?  THis is pretty sad if i can't render such a small scene on decent card.

The primative with no textures and no lighting took 3GB of vram to render???  Vram usage was at .4GB before starting the render.  That seems hugely excessive no?

kenshaw011267

mid_knight said:

yes.. a single primative cube renders on both GPU's just fine

Is there a way to find out how much vram a scene requires before hitting render? or after even?  THis is pretty sad if i can't render such a small scene on decent card.

The primative with no textures and no lighting took 3GB of vram to render???  Vram usage was at .4GB before starting the render.  That seems hugely excessive no?

There is a basic minimum overhead for the scene, lighting model and scratch memory for the CUDA pipelines. Those are fairly static so every scene no matter what is in it will have that sort of memory usage.

That scene does seem a bit small to cause a fall to CPU. Check the subD of each element. Every increase in subD quadfruples the size of the items geometry. That can burn through VRAM in a hurry.