OTOY Forums

Hello Everyone,

I've been testing the demo for Octane and LOVE IT! I'm planning on purchasing as soon as the Rhino Plugin is released in beta. Which brings me to a functionality question -

I'm in need of a new laptop, and would like two 780m cards. However, every manufacturer that I've found only configures these in SLI. So, my questions are:

1) will Octane utilize BOTH cards if they are SLI enabled?
2) can I still tell Octane to use just one while editing and then select both for final rendering?
3) I read this on Nvidia's website about the new CUDA toolkit, and am wondering if it no longer matters whether or not SLI is endabled: "Each GPU in an SLI group is now enumerated individually, so compute applications can now take advantage of multi-GPU performance even when SLI is enabled for graphics."
https://developer.nvidia.com/cuda-toolkit-23-downloads

I've got a 780 in my desktop and really would like two 780m's in a new laptop, so I don't have to take a performance hit. Please advise if the SLI will be an issue?

Thank you!

Hi, SLI can be disabled in the NVIDIA driver control panel, so it shouldn't be a problem to get a laptop with SLI capability. You can just turn it on/off as you want anyway...

SLI is best turned off for octane.
As the CUDA driver update says, whether SLI is enabled or not, both cards are separately visible to octane and you can turn them on/off as needed.

Thanks
Chris.

This is great news! I really need a laptop with some performance and was very worried about SLI. I'm glad it's not an issue! Thanks Chris.

I do have two more questions.

I've read on your forum that the Fermi Architecture is still faster than Kepler. If that is the case, are their plans to change that?

I was planning on geting two 780m's but they are Kepler. Would two 580m's be faster? On paper, just looking at specs, the 580m's look slower, but . . . not sure how Octane utilizes everything. I've got a 780 in my desktop and Octane FLIES on it. Thanks.

Well, this was a hot/tricky topic.
The 600 series was not as fast for octane as the 500 series - there was nothing we could do about this, it was just the way the hardware worked.

The 780 is different. It's not too far from the titan in speed - it should be about 40% faster than a 580. Not to mention having 4GB of VRAM and twice the texture count limit.

The 780m looks to be like an underclocked desktop 770. So it's a good thing your going with SLI to make sure you have good performance. My instinct is that two 780m's will be a littler faster than a desktop 780, but not by a huge amount.

Thanks
Chris.

Perfect, this is exactly what I was hoping for. Thank you again for your help!