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Hi, everyone,

I have two questions about multi-gpu.

Before buying a license, I have two simple questions.

First, if I use two different graphic cards, like 460 gtx 2g and 9800 gt 512mb, and I use multi-gpu, can I assign data to only 460gtx 2g? Or sometimes can I assign data to only 9800 gt 512mb? 'cause I need to use a graphic card, like modeling or shading..

Second, if I use same graphics cards or different cards, can I combine two cards' vrams?

I have one more. if I rendered in single card, later can I render in multi-gpu? There is not like an option like an import. Or can I change an option in device manager during rendering a scene?

Hi there!
1. You can assign whatever the card you want to render or all your cards at the time.
2. The rendering vram will be equal to the lowest of the cards you assign to render with. In your case, when you assing only the 460 you would have 2gb of vram, but if you assign to render with both of your cards you'd get only 512mb of ram.
Usually u would prefer to render only with 460 and let the 9800 to move your system graphics.
Hope this helps.
Cheerio

Thanks for your reply.
I don't understand "Usually u would prefer to render only with 460 and let the 9800 to move your system graphics." That means that I need to remove it?

And also one more question. If there are three cards and they are all different cards, like 460 gtx(2g), 9800 gt(512mb), and 9500 gt(768bm), then if I render in two card, octane will get the lowest one of vrams? Then I need to buy cards with same amount of vrams, if I want to render a large scale resolution with a complicated shot?

Thank you again.

ttaberna wrote:Hi there!
1. You can assign whatever the card you want to render or all your cards at the time.
2. The rendering vram will be equal to the lowest of the cards you assign to render with. In your case, when you assing only the 460 you would have 2gb of vram, but if you assign to render with both of your cards you'd get only 512mb of ram.
Usually u would prefer to render only with 460 and let the 9800 to move your system graphics.
Hope this helps.
Cheerio

teyleecom wrote:Thanks for your reply.
I don't understand "Usually u would prefer to render only with 460 and let the 9800 to move your system graphics." That means that I need to remove it?

No, that means, that you can select the 460 for rendering only and if your 9800 is connected with the display(s), you don't have any lag in display performance, while your render. If you would have only 1 card or would use both cards for rendering then each calculation pass basically blocks the graphics card(s), i.e. no framebuffer changes get through and everything feels very sluggish.

In a nutshell: With your configuration, I recommend to use the 460 for rendering only and the 9800 for your normal display tasks.

And also one more question. If there are three cards and they are all different cards, like 460 gtx(2g), 9800 gt(512mb), and 9500 gt(768bm), then if I render in two card, octane will get the lowest one of vrams?

That's correct, i.e. you would be able to use up to 512MB if you would use all three cards.

Then I need to buy cards with same amount of vrams, if I want to render a large scale resolution with a complicated shot?

Thank you again.

Yes, that's correct, but I recommend to buy cards with similar performance levels (2x GTX460 for example), because the speed differences between different generations is huge.

Cheers,
Marcus

abstrax wrote:
In a nutshell: With your configuration, I recommend to use the 460 for rendering only and the 9800 for your normal display tasks.

That's what I ment
Thanx Abstrax for replying

Thank you for your quick answers.

But I have one question. When I rendered a shot in a single gpu, later can I change it in multi-gpu?

Thank you.

teyleecom wrote:Thank you for your quick answers.

But I have one question. When I rendered a shot in a single gpu, later can I change it in multi-gpu?

Thank you.

Once the render engine is started the multi-gpu configuration is locked, so you can't change it until you start a new instance of octane.

Radiance

Guys I dont get one thing...so this will sound very stupid.
One GTX card inside my computer is enough to run Octane right?
Im asking this couse I read here "one card for system, and anotehr one for Octane"
Thanx!

p.s. wich option should I look when buying a new graphic card, its memory or speed?

picajol wrote:Guys I dont get one thing...so this will sound very stupid.
One GTX card inside my computer is enough to run Octane right?
Im asking this couse I read here "one card for system, and anotehr one for Octane"
Thanx!

p.s. wich option should I look when buying a new graphic card, its memory or speed?

... one card is all you need! as octanerender (of course) acquires a lot gpu power, a second card (even a cheap one) will help to get a more responsible system, while rendering, esp. if you use win 7. the only thing to pay attention is, to not mix ati/amd and nvidia cards... octane depands on cuda and is nvidia only (and nvidia drivers are blocking cuda access, if they detect and ati/amd card in the system).

imo you shold look for speed ... and ... memory as all of your scene (polys & textures) needs to fit into the available vram of the card, it sets the limit for how complex a scene can be. and faster is always better i'd say. i did put together a benchmark with various consumer cards a few months ago, which may help a little: http://dl.dropbox.com/u/10375307/octane_bench1.pdf

Thanx t_3!
So your advice is the keep my current GeForce GT9600 and buy eg. GTX 560 and use it for Octane.
Im sorry to ask you this also, Ive looked at my local shop for GTX cards, but there are so many types of the same card that I just don t get?!
Problems also with the pricing wich I dont get, egsample 2 cards:

ASUS GeForce GTX 560 Ti DirectCU II, 1GB (GPU [MHz]830, memory [MHz)4000)
and
GAINWARD GeForce GTX 560 Ti Phantom, 2GB (GPU Clockspeed : 822 Mhz,memory [MHz] 4000)

Same price!
For a person with no hardware knowledge 1GB vs 2GB, I clearly see hows the winner.
But there has to be a trick, I mean for the same price*!??