I haven't had a chance to play around with multiple adapter configurations yet, as I do the majority of my development on a laptop, but I was hoping a few people here might have and could answer some questions. Can a single DX10/11 Device object be used to render to monitors connected to different video cards, or do I have to create one device per adapter? Does SLI/Crossfire count as just a single adapter, or does it show up as 2? And in the case of it just being one adapter, are there any special device setup requirements? From reading the DX10 docs, it seems the only resource that can be shared between multiple devices is a non-mipmapped 2D rendertarget. Does DX11 have this limitation with multiple devices too?

Devices are tied directly to adapters, so you will need 1 device per adapter. You can enumerate them using DXGI.

An SLI system will show up as one adapter, however you will likely have trouble leveraging it since DirectX doesn't expose any functionality that would allow you to indicate how SLI/CrossFire are supposed to split the work up. Drivers usually have per-application settings that have been tested and enabled by hand. You'll have to poke more into this.

DX11 is limited just like the others. You can try and test out sharing of other resource types and see if the driver lets you. But DirectX only enforces that a limited number of formats are supported for rendertarget sharing.

Thanks DieterVW. Had a feeling i might need 1 device per adapter. DX gladly lets you use 1 device for multiple monitors if they are on the same adapter though, this is the only case i've been able to test with my current hardware :)