Solved by sharkdeng in post #2 
              
              
                Wow, solved! I checked the Efficientnet-pytorch source code and suddendly found I should turn the model to eval() mode. 
Now the predictions are same!! 
model = efn.EfficientNet.from_name('efficientnet-b0')
model = model.to(device)
_ = model.eval()  ## hey, look here!!

img = torch.ones((2, 3, 680, …