second GPU Help needed Tweet

[marek999]

Hallo,
First of all I want to say hello to the forum and the octane/otoy community.
Was not quite sure where to post my hardware specific question on this forum... hope this is the right spot

I have not so much experience in using a GPU render like octane and all the hardware "stuff" that comes with it. so I hope somebody can help me with my question.

Right now I am using a GTX 780 graphics card with 3GB of Vram and I want to buy a second GPU. So, my question is:

Can I buy for example a GTX 980 with lets say 6GB of RAM and just add it in Octane ( like in the Modo plugin under "cuda device settings" - add 2nd device )? And render with the power of 9GB ?
Or do I need to have two same Graphic Cards with SLI two use the whole potential ?
and if so will be than the old 780 useless? and octane will not address it?

thx

[kavorka]

First off, Octane doesnt use SLI, so don't worry about that.

Octane doesnt care if the cards are the same, so you can use your 780 and 980 together. However, it does not add the RAM together because the data has to fit in both cards simultaneously. What that means is that your max VRAM is equal to your lowest card.

You might want to consider using a dedicated display card so Octane will run smoothly as well.

Also, RAM doesnt affect speed at all, it just allows you to use larger scenes with Octane.

[marek999]

thank you very much for your reply!

so what does exactly speed up my render time? Like faster sempling.
Or isn't there anything like that? and sample calculation is just always the same and
it just depends on the poly count of my scene how fast the rendering is.

ou might want to consider using a dedicated display card so Octane will run smoothly as well.

my 780 is a dedicated. Or do you mean a specifc CUDA card?

[kavorka]

thank you very much for your reply!

so what does exactly speed up my render time? Like faster sempling.
Or isn't there anything like that? and sample calculation is just always the same and
it just depends on the poly count of my scene how fast the rendering is.

ou might want to consider using a dedicated display card so Octane will run smoothly as well.

my 780 is a dedicated. Or do you mean a specifc CUDA card?

For the display card, it is best you have a cheaper card that just handles your normal display (a $100 card usually works fine). If you use your display card as a render card in Octane, your computer will be unusable or very slow while rendering. If you have a dedicated card for your normal display you will have a much better time in Octane.

Speed is mostly dependent on the card you are using.
Here is a list of speeds users have gotten with the same sample scene in Octane:
https://render.otoy.com/octanebench/results.php


Polycount really has little to no difference. what matters more is how much bounce light vs direct light. More complicated lighting with lots of bounced light (interiors etc) are much slower than a product shot in the open.

[marek999]

thank you. I wil check the benchmark and search the web for further information.