The V7 client is usually able to determine multi-GPU setups and use them appropriately. Each GPU will work on seperate Work Units. Typically, multiple GPUs from the same vendor will not cause any problems, but sometimes V7 can get confused with a mixture of GPU vendors. This usually manifests itself with Work Units being assigned to the wrong GPU and immediately crashing. If this happens, visit the Folding Support Forum and the volunteers there can help you adjust your configuration.
