What happens when...

[Macker]

You hit the VRam limit on your GFX card? Does the render simply start loading it into ram, as it would in the normal production renderer? Or does it stop the render?

I don't currently have a CUDA enabled card, and it's getting pretty old these days so i rarely use RT. The VRam I've got on board is 3gb, but almost all of my scenes will use more than that.

[Morbid Angel]

The ram and vram is not shared, its a big limitation in gpu rendering nowadays. If you hit the limit, expect your video to start dropping out, this is what happened to me last time, the video driver has crashed a long with all the applications running at that time. I think its pretty much the same as if you run out of regular ram during rendering and your software will crash and your os becomes slow for a while since no more memory left in the pool.

[Macker]

Damn, GFX manufacturers need to address this. I need 12gb minimum, really.

[Morbid Angel]

if you browse this forum you can read a bit about other peoples experience with gpu ram. I don't think that vram = ram. People reported being able to pack quite high res scenes into less vram then regular ram. With that said though, one of the biggest issues is the textures in memory, if you plan to have many large res textures this will surely kill the ram.
Im sure vram will increase with time as you can already notice titan has 6 gb.

[Macker]

Yeah, i'm sure it will; but the price difference between one titan and two..! Plus dual titans for my colleagues; it really isn't likely that it'll happen unless we can get hold of a 12gb card off the shelf.