2 smaller graphics cards or 1 big one?

Hey there all, looking to update either my work's mac or pc with a graphics card to render in Blender's Cycles renderer (since I'm relying on the CPU at the moment and want to use GPU).

So since Blender's Cycles only supports certain Nvidia cards I guess I have these questions:

1) Would 2 smaller graphics cards be better off for faster rendering compared to one large one, eg would 2 GTX570's be better than one Titan in regards to rendering speed and cost?

2) Since my mac is my main work computer could these kinds of graphics cards be put into it, if it's a:

Model Identifier: iMac12,2
Processor Name: Intel Core i5
Processor Speed: 3.1 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 8 GB

whereas my pc is:

ACPI Multiporcessor x64 based PC
Intel Xeon CPU
2.26 GHz
12 GB RAM
XP
NVIDIA Quadro FX 1800

3) Does anyone else have a similar setup and could recommend me graphics cards to render from GPU in Blender's Cycles?

Thanks in advance.

2. You're not going to get 2 video cards into an iMac.

You're also not going to put an off-the-shelf desktop video card into an iMac.

1. In relation to your windows machine - you're going to need to start searching the web for benchmarks on the specific cards you are considering. You "might" get some feedback in a Blender specific forum.

pancreasboy said:

2) Since my mac is my main work computer could these kinds of graphics cards be put into it...

Click to expand...

Your iMac is basically a closed system in terms of increasing its cpu and gpu abilities. All your really able to do is upgrade the ram & hard drive. If you need more processing power out of your iMac...you need to purchase a newer/faster imac.

- Nick

Ok thanks guys,

so from all the posts I've read so far here's what I've discovered...

No to the mac in regards to 2 graphics cards or fitting in a card of my choice (unless I maybe wait for the MacPro).

For my PC I need to check a few things, like do I have 2 PCI Express x16 length Slots to hold the cards and a good enough PSU (since dual cards might overheat), and is my CPU a single, dual, quad core?

I'll try to get a photo inside my PC, but the **** thing is locked shut thanks to the uni I work for. But here's a few screenshots of my setup...





The other option is make a render farm or use a online render farm service.

Another question too is can CUDA in Blender use SLI graphics cards, cause I'm getting mixed reports...
Blender Cycles best hardware ? Using the Benchmark spreadsheet analysis | Oenvoyage's Blender Blog
Blender Cycles GPU Hardware FAQ | The Dedicated System Agnostic