How does multi GPU work?

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julianb
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Hi all,
I am kind of lost here- I checked several threads but still can not find an answer...
I have a GTX 275 at the moment and would like to buy in addition GTX 470 (or even GTX480). What I do not know is:
1. Do I absolutely need to connect the two cards using a SLI connector or no connection is needed?
2. Can I connect two different cards (GTX 275 and GTX470) via SLI connector?

Thanks a lot.
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YoonKyung
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julianb wrote:Hi all,
I am kind of lost here- I checked several threads but still can not find an answer...
I have a GTX 275 at the moment and would like to buy in addition GTX 470 (or even GTX480). What I do not know is:
1. Do I absolutely need to connect the two cards using a SLI connector or no connection is needed?
2. Can I connect two different cards (GTX 275 and GTX470) via SLI connector?

Thanks a lot.
You must not connect GPUs with SLI, if you want to use a CUDA application, Octane.
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julianb
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Thank you for your response, YoonKyung
So what- just insert the two different video cards in the PCI-E slots on the motherboard and adjust Octane's settings?
Is that it?

Cheers.
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Krisonrik
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julianb wrote:Thank you for your response, YoonKyung
So what- just insert the two different video cards in the PCI-E slots on the motherboard and adjust Octane's settings?
Is that it?

Cheers.
I remember seeing one of the post saying Octane can access different types of GPU. So yeah I think you are good to go.
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havensole
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Yup, dont connect them in SLI. NMake sure that physx is enabled in the nvidia control panel and setup the mult-gpu in the device manager of octane. Pretty easy.
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radiance
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havensole wrote:Yup, dont connect them in SLI. NMake sure that physx is enabled in the nvidia control panel and setup the mult-gpu in the device manager of octane. Pretty easy.
make sure that physx IS NOT enabled ;)
little typo there havensole.

Radiance
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Amplitude
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i'm sorry Radiance but I had the case yesterday when I installed my second gpu:
if PhysX is NOT enabled, Octane doesn't NOT see the second gpu!

I went to a complete drivers reinstall before understanding that the PhysX setting was causing the issue.
Is it a bug?
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radiance
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Amplitude wrote:i'm sorry Radiance but I had the case yesterday when I installed my second gpu:
if PhysX is NOT enabled, Octane doesn't NOT see the second gpu!

I went to a complete drivers reinstall before understanding that the PhysX setting was causing the issue.
Is it a bug?
that's very strange as here it's the inverse.
if we enable physx on our multi-gpu machines here, the 2nd card is invisible... ?!

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Amplitude
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I believe you, very strange that the situation can be inversed depending on the rig you use.
My board has an i975X chipset and SLI is not supported, don't know if it helps...
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julianb
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Thanks for the replies, guys...
As to the physx settings- I will try both ways and see what works and what not.

Cheers.
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