Oh yes! I’m absolutely agree with you! I added images, labels = images.to(device), labels.to(device) before net(images) and the process runs to the end  and So I tested this code with GPU transfer and none, it’s ok but when I pick up the duration of the program, GPU : 100sec and CPU: 73sec, so firstly I think it must be the opposite and the gap more huge no ? Normaly, with GPU, the program takes fiew seconds in a perfect world