Does Unity support CrossFire or SLI?

Does Unity support CrossFire or SLI setups for Video Cards?

What can I do to that advantage of having two or more GPUs?

To Unity (or any other 3d app) Crossfire and SLI configurations are presented as a single GPU.

You can follow the best practices to possible improve performance using SLI/CrossFire are described by nVidia and ATI in these guides:

Some things you can try to improve performance based on their guidelines are:

  1. Don’t share data across frames, Don’t read back any data, Clear buffer:
  • Don’t use “depth only” or “no clear” flags in Cameras.
  • Re-render all render texture contents each frame.
  • vClear any temporary RenderTextures.
  1. Don’t sync to any less than as many frames as there are GPUs. You can either set VSync to 0 (don’t sync) or 2 (for 2 cards).

The impression with SLI/CF is that it really only brings performance improvements for games where NVIDIA/AMD have tweaked the drivers specially for those games.

If they haven’t, most likely SLI/CF will bring very little (or none) additional improvement.

That said, it’s really easy to try. Just run your game on SLI/CF system and see if it’s faster than without it. If it is - great! If it isn’t, that could be something you need to talk with NVIDIA/AMD about.