How to find out how much GPU memory your scene is going to take ?

[JezUK]

I'm playing with a scene, using RT, hit render and I get the error message effectively saying that I'd run out of memory on my GPU-0 (I have two identical GPUs).

Is there any way I can find out how much GPU memory a scene is taking or going to take BEFORE I start to render ?

It'd save having to restart my computer as it becomes almost unusable if/when your scene does run out of GPU ram.

[Alex_M]

This sounds strange. I've never had to restart my PC when a scene doesn't fit in the VRAM. My PC runs perfectly well after an out of video memory error message. I'm using the nightly however and just one GPU. As to how to check if it would fit - no idea, I'm curious too. So far I just hit render and have my fingers crossed that it makes it within my measly 4GB of VRAM which is even lower if you consider that stuff already occupying the VRAM like viewport, UI etc.

By the way, what is your experience and observations with rendering on 2 x GTX 1080 ti? Is it faster than your 5960x and in which scenes? I plan on buying one 1080 ti and if it works well maybe a 2nd one. According to my estimations just one 1080 ti would be 2 times faster than GTX 980 which is quite a nice upgrade for me. I've found that in about 50% of the scenes that I test (interiors, exteriors, product shots especially), my GTX 980 is about than 50% faster than my CPU (which is admittedly quite old now). I even manage to render some small to moderately large exterior scenes with 3d vegetation comfortably on my GPU even with its 4 GB of VRAM and they render surprisingly clean even after 2-3 passes have elapsed. I would imagine having 11 GB of VRAM should allow one to render quite a large range of scenes? To be honest, I very very rarely see my PC RAM ever spiking over 12 GB on any scene, even large exterior ones with 3d vegetation so I'm an optimist.