Solved by ptrblck in post #2 
              
              
                This sounds like a float precision issue. 
You’ll get the same for different orders of operator execution: 
torch.set_printoptions(precision=10)
x = torch.randn(100, 10, 100)
x1 = x.sum()
x2 = x.sum(0).sum(0).sum(0)
print(torch.abs(x1-x2))
> tensor(0.0001220703)