What happens when the Video Card RAM is full

lancelmartin_cf51987037

I have two Titan Z's that I do all rendering on.  Until recently, even if the scene exceeded the RAM on the card, the cards sill rendered the scene.  For some reason, now,

after about the first 15 to 20 iterations, even on scenes with only one figure... the whole render switches over to the cpu.  CPU fans start up and the render slows to a crawl. 

It's like the cards just say ... OK we're done here and give up.  I've got them set to maximize 3d performance and have tried with them both with sli and without.  Anyone know of any other Nvidia settings that I could be missing?

Or ... is a video card just going out?

Richard Haseltine

I believe that the figures that seemed to be exceeding the RAM capacity of the card were based on uncompressed textures. As for why a single figure would dump to CPU, are you leaving previous renders open? Do you have a very high Render SubD level set?

JD_Mortal

Do not use SLI. You want each card to render individually, not as one unit rendering the same thing.

You have exceded the physical RAM of the cards, so it falls-back to the CPU. (It does not know this until it tries to "fit it in memory", as what goes in, is not exactly what it uses inside the card's RAM. There is another layer of compression after any compression that DAZ has done.)

Unless you have massive reflections or multi-layer obstructions over every object... I would try rendering specific things, individually. It does require a little bit of management of surfaces, but it makes it possible when it normally isn't, for GPU rendering.

Other tricks...

Reduce render-quality of distant objects. DAZ defaults to something like 2 for on-screen editing, but bumps it up to 3 or 4, for actual rendering. (Subdivisions) Even when some things, subdivided, don't actually gain any more detail. (Items without NURBS and CURVES, which are manually created angles, will not change shape, unless distorted by something like a bone-rig or a deform tool.)

You can strip-out bump-maps and normal-maps on anything distant. You are not actually going to see the micro-surfaces on them, as they would be many pixels of light-deforms within one solid pixel.

You can also force, (I think), on the beta-version, to use a maximum texture-size. (Not sure if the current non-beta build also has that advanced option.) Great if you don't have any super close-ups.

Eyes... Unless your eye consumes more than 64x64 pixels, manually reduce the mappings to a 64x64 pixel-size. (I see some still using 2048x2048 and 4096x4096, for some crazy reason, including the unseen diffuse, specular, bumps and normals at the same sizes. There is over 6 reflective layer passes on the eye alone. Confirmed by manually setting "reflections" to 7, instead of infinate. Less results in solid black eyes. Complete overkill for no real gains.)

Hide unseen items, even if out of the rendering view, they are used to render the image. (Reflections and Refractions) Even if you don't think you have reflections and refractions, it assumes you do. Eyes do both, on various layers.

There is a tool that can even help do the grunt-work in just a few clicks. (Reversable, so as to not actually alter the scenes permanantly.)

This reduces polygons. https://www.daz3d.com/decimator-for-daz-studio

These can reduces image-quality and handles things like unseen normals and bumps, etc... 

https://sites.google.com/site/mcasualsdazscripts3/mcjalttex

https://www.daz3d.com/forums/discussion/137161/reduce-texture-sizes-easily-with-this-script

This is the "texture compression" I was talking about. It would be in the advanced tab, on the iray rendering pane.

https://www.daz3d.com/forums/discussion/71594/is-there-an-easy-way-to-reduce-texture-sizes-for-rendering-in-iray

http://blog.irayrender.com/post/54506874080/saving-on-texture-memory

For more manual playing... Trying to figure-out which things to remove... (This is a great detailed set of info on each of the IRAY shader settings.)

http://sickleyield.deviantart.com/journal/Iray-Surfaces-And-What-They-Mean-519346747