Greetings,
Whenever I watch a tutorial from Blender Guru or Blender Cookie, they all have these amazing graphics cards that render things in cycles REALLY REALLY fast. I was thinking of getting a new graphics card, and was wondering how many Cuda cores do I need to make Cycles usable? Or what graphics card specifically would be good for Cycles, that doesn’t cost too much. I’m not really sure if the Cuda cores make it work better for Cycles…
A few time ago I had the same situation.
I had a Core Duo 2 1,8Ghz with a Geforce GT 9500 - no CUDA… 
And like you I saw the tutorials.
I bought the Geforce GTX550TI.
With my old system it made problems, bluescreens and so on.
Now I updated the Rest with a Intel i3 and now everything works stable.
The card is very good in price/performance - for me it were 110 Euro.
And the Renderer-Preview works fine. Naturally you cannot render a whole scene in preview with this but for experiments with cycles to become better with this this is very good. I don’t want to miss it.
I think you have to look for, what Cuda is in the card: in my it’s 2.1
In blender wiki is written:
NVidia CUDA is supported for GPU rendering with NVidia graphics cards. We support graphics cards starting from GTX 2xx (shader model 1.3), however it is recommended to use a GTX 4xx or GTX 5xx card (shader model 2.x), since only those are likely to give good speedup, earlier cards are often slower than just using the CPU. Shader model 1.3 cards also do not support some Cycles features, see below.
…on this site: http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/GPU_Rendering
On the nvidia-site you can see what card has what CUDA.
And I think you should take an least 2.0 or 2.1
New features what now come up with newer releases need 2.0 and this will go on…
Hope this will help you.
Greetings,
Nahuta
Awesome, thanks for your help!
I bought Nvidia GTS 450 passive and I’m satisfied with it.
It is relatively cheap and cuda compute capability is 2.1
It does not need powerful power supply.
I can still do my audio stuff because it is absolutely quiet.
Rendering is about 4x faster than 3.0GHz Dual Core
What you need to consider is also VRAM, or Video RAM. Your entire scene (models, textures!) must fit onto the cards memory.
Recently i bought an EVGA Geforce 270 GTX, with 2,5 gigabyte VRAM, and i’m not disappointed! Having almost the same power as the 280 GTX it was an extremely good deal.
Get a card with a least 2 gb memory.
Seeing you need ‘compute version’ 1.3 or higher for using things like AO, vector and normal layers, I recommend you buy a 4xx- or 5xx-series card as 2xx series is only compute version 1.1…
But memory is as important or more than CUDA cores, so for serious use buy a card with 2Gb or more VRAM. There are reasonably priced Nvidia GTX560Ti cards with 2Gb (and double the CUDA cores in comparisson to a GTX550-card).