Yes, start with the cables. Use a minimum number of components. Swap components where you can and only swap one at a time. A 2-slot graphics card has just enough space below it for 25 mm thick fans, so any card that is thicker restricts you to slim fans. My son's M1 has two of the slim Noctua fans (as intakes) under his 1070 and they helped lower his GPU temps. He didn't need to use slim fans, but I like that there's a small gap between the fans and the graphics card cooler.