If I set torch.device(“cuda:2”) or torch.device(“cuda:3”), I got error: tensors must be on the same device. If I set nn.DataParallel(model, device_ids=[1,2,3]).cuda(), on first GPU (with index 0) free memory decreased (same as I run training on it) and after that raise error: tensors must be on the same device. In training block of code batch of images send to GPU (input.to(device)). May be this happen because processor have only 2 cores?