[Bf-cycles] cycles, some questions about GPU

Sebastian Röthlisberger lalli at gmx.net
Wed Nov 16 14:20:21 CET 2011

Hi Brecht and Followers,

i'm currently building a new (triple Boot, osx, linux, win) computer, mainly for use with blender/cycles.

So there's the Thing i'm struggling a bit: The GPU.

Since those question will probably come up for other blender users as well i would like to ask you once and put a summary on my website (bwide.wordpress.com) for everyone.
I did a good amount of searching the web for answers, but haven't found.

So the Questions are:

Cycles GPU Rendering currently is limited by the amount of available memory on the GPU, as far as i know. 
1.-will cycles be able to render scenes bigger than the available Memory on (one) GPU?
	1b.-if, in future, cycles uses multiple GPUs will it be still limited by the max amount of memory on one GPU or by the sum of all?

2.-Is the rendering speed mainly determined by GFLOPS?
	2b.-if not, can you tell me what is?

3.-Does Cycles make use of any "newer" NVIDIA technology? I mean will an older GPU (cycles ready) with same specs as a theoretical new One render at about the same speed?

4.-Cycles doesn't care about Nvidia SLI, "just" (will) use all GPUs, right?

5.-Will cycles care about different GPUs (for example 1xOlder Cuda, 2xNew Cuda)

6.-Will/might it be possible to mix Cuda and OpenCL GPUs?

7.-Is there a chance that, in future, currently older GPUs like gtx 295 will drop out of Cycles support? 

8-. just for private use: Do you recommend any GPU?

Just wondering:
9.-I know you can't tell, but when you think will multiple GPUs be supported (CUDA)?

10.-Do you know/predict anything about significant speed differences (of cycles) between CUDA and OpenCL?

11.- Between 0-100%, approximate about where is cycles development at the moment.

That's it for the moment.

And i'd like to thank you for your amazing work on cycles and blender in general. 

Have a nice Day.


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