SLI

[Ryoku]

First off, hats off to the creation of Octane, I think this is one of the most exciting and sensible ideas well...ever. I've recently been getting only more and more frustrated with rendering with mental ray as the speeds are depressing, not to mention having small roadblocks that take careful observation to overcome too many times. I plan on building a new rig very soon and at first debated over whether or not to get a i7 980x; then I remembered somebody on the cgsociety forums who posted a thread on Octane [genius!]. So instead of spending all that extra $$ on the CPU, I feel investing in the 470/480 and going with a i7 930/960 is the way to go. Only thing I wanted to ask is if I should go with a single 480 or dual 470s. I've never run GPUs in SLI or crossfire before and I heard it might pose some extra problems. But my only real reason for buying a new rig is to help stabilize my workflow, and Octane looks like the perfect way to help mediate my artistic vision with reasonable approach. Can't wait to purchase the beta, and once again amazing work. =]

[havensole]

You don't need to worry about SLI as Octane wont work with SLI enabled. Its just the way that CUDA works. Yes it will use multiple GPU's at the same time, just not with SLI enabled. The big question about which GPU's to get will depend on how much RAM you think you will need. the gtx480 has more and run a bit faster, but 2x gtx470's will run faster then 1 gtx480 if you don't need the extra 300+ megs of ram. I haven't run proper stats on this as I don't have a gtx480, but I do have 2x gtx470's. It is friggin fast!!! I'd recommend that you get a motherboard with an nVidia built on gpu to run you main display setup and leave the gtx470/480's strictly for rendering. This will greatly improve your general navigation and OS work. You will ove how fast Octane renders your work.

[Ryoku]

Thanks for the reply. =] So essentially 2 470gtx would be the way to go? I was a bit confused at first but I think I understand now. Octane will only utilize 1 of the cards vram but both cards can be used to speed up the rendering/UI? Only thing I'm worried about is if any particular scene happens to pass 1.2gb, and how it can be resolved in the future. Can't wait to use it!

[radiance]

Hi,

with 2x GTX470 cards you will get near double performance.
but you will only have the 1.2GB of video ram available as the data needs to be stored on both cards.

we would advice, if you want to make larger scenes, to use a GTX480 card instead,
or if you're savvy, try using procedural textures in the soon to be launched 2.2 to save gpu memory.

Radiance

[havensole]

If you really really really need that a ton of ram for textures are really huge geometry scenes you will want to look at maybe Quadro or Tesla cards. I really haven't had any scenes yet that go past the 1.2gb mark yet, but I am sure once collada type formats become enabled we will see more geometry data needing to be loaded in (for animation data). If by chance you do have a scene that goes above the vRam cap you might see a couple of things. It might refuse to show you anything in the preview window, refuse to load the mesh, or crash. Granted I haven't had an issue with any of these since I moved from my old 8800gt and much older versions of Octane so I can not say for certain if this will still be the case. Radiance can tell me if I am wrong.

[Ryoku]

Thanks for the advice! Well I just ordered my rig, and went with 2 470Gtx. I'd rather go with better performance than have an extra 300MB of space which I'll debatably need anytime soon. I can always upgrade if it comes to that. What would be the poly and/or texture size limit for 1.2gb of vram at the moment? Any of my current 3d models have not surpassed 2 million. I'm a self-taught 3d artist and I've only begun recently uvmapping and texturing my models; really excited to begin playing with Octane including the procedurals, but will be waiting atleast 2 weeks until the computer arrives so all I can do now is brainstorm and perhaps work on some new ideas.
By the way radiance, is there any chance in the future that Octane will support SLI or there some unworkable hardware/software roadblock that's preventing that?

[havensole]

Radiance would have numbers if they exist. I am in the same boat as you for the most part (self-taught and 2x 470's). I know I've had some pretty huge scenes in there, even with my gts250 1gb, and it worked fine. Where did you get your rig from?

[scarecrow2k6]

Sorry for shortly hijacking the thread, Radiance does the latest demo have multi GPU function? Thanks.

[havensole]

I'm not Radiance, but yes it does. You have to set it up in the device manager. It doesn't automatically assign it to use all GPU's.

[scarecrow2k6]

Havensole thanks for your reply, can you please tell me how the multi gpu works in octane? I mean it it going to share 1 scene between 2 cards? I ask this because I am using a GTX 470+ GTX 285, one is being used 98% and the other 50%. Thanks.