GPUs

[Elele]

Howdy

Been playing with the octane demo and really like it. However I didn't built my pc with this renderer in mind. Atm I have a GTX670 with 2 Gb memory. I still have a PCIE slot free, so I was thinking of getting a second card, but I dunno how this works. I read that you're supposed to get the same card (gtx670) to use multiple GPUs. Is that also true for octane?
If I do get the same card again, will the available memory stack (2Gb+2Gb=4Gb)? Or does each card need to load the entire scene and so the total memory would still be 2 Gb?

Thanks,
Elele.

[FooZe]

Hi Elele,

1) For SLI/Multi-GPU gaming, the cards need to be the same, but this is not true for octane. Octane sees GPU's as CUDA devices that are independent of each other.
2) The total scene size will still be 2GB. Both cards need a copy of the scene to work on in their own VRAM. Also you are limited to the lowest capability of the cards you use to render in other respects as well (compute capability, texture count limits). See the first item on the FAQ page for more details.
http://render.otoy.com/faqs.php

Thanks
Chris.

[Elele]

Fiddlesticks! I was afraid the memory wasn't going to stack, 2Gb is quite low...
So I could get a 6Gb card (not a gtx 670) to render and keep the gtx670 to run the other stuff? Is it difficult to assign the GPU tasks like that, or is it just a matter of ticking the right box in the options?

Thanks,
Elele.

[FooZe]

For octane, yes, it's as simple as ticking the cards you want to use for rendering.
I would suggest pluging your monitor into the 670, so other apps will use this one (windows etc). Leaving the full 6GB on the titan free for octane.
For scenes small enough to fit in 2GB you can of course enable both of them for extra speed.

Thanks
Chris.

[picajol]

One question.
Regarding memory issue, many talk aboth texture impact on the memory but looking at my usual interior job I have no more then 20 textures aplied to scene and images not beeing larger then 5MB. Thats only 100Mb on textures*!*!?!
Whats the problem then then?!

[Zay]

When you hit the limitations - then you have a problem

[Elele]

Ok, thanks for the info
I usually have pretty small scenes, but they are heavely texture based and the textures aren't really optimised for memory usage. I'd didn't really worry about this before, but from some tests with the demo I saw I was already at 1300Mb for a pretty small scene. But for now my GPU will do the job... till i can save up for a bigger one
BTW, tried to buyh octane this weekend with a credit card but i kept ending up on the paypal site. I have a paypal account, but now I have to wait till the money is transferred

[picajol]

ok but can you tell me are my observation ok or is the .jpg texture filr (5mb) multiplied when loaded in the scene?

[Elele]

Hmm, I think I see what you mean. When I load a texture image that is 30Mb, the image texture size in octane preferences jumps by 100Mb. So it seems it is being multiplied somehow. Dunno what is going on. Is there a way to turn that off?

[Zay]

ok but can you tell me are my observation ok or is the .jpg texture filr (5mb) multiplied when loaded in the scene?

It's the pixels amount that counts and not the file size.
http://render.otoy.com/forum/viewtopic. ... 561#p35561