EEVEE seem not to benefit from multiple GPUs for rendering Recently I have built a new workstation PC with dual GTX 1080 Ti. I know that in Cycles, each GPU renders 1 tile but I'm not sure about EEVEE. I tested it and it seems that even if I have checked both GPUs in user preferences EEVEE still uses only 1 GPU. I tried opening 2 instances of Blender 2.8 and set different GPU in each but the result was same; it keeps using one GPU only. This might not be implemented yet or SLI bridge might be required, I am really not sure. Do you guys have any experience with it? Has anyone done some rendering using SLI?
Multi GPU support for EEVEE is a really hard goal to atchieve because of the nature of the technology. It is not being worked on at the moment and it is not planned for any time soon. EEVEE might benefit from SLI or Crossfire setups. It would be logical to wait untill it's realeased to test that though. I believe it is safe to assume that EEVEE will definitely not be able to use multiple GPUs that are not connected with SLI/Crossfire for real time rendering when it is released or any time soon after.