With the PSU in place on the top shelf, I drew around it in pencil. I then removed the fan cover and from this I could work out where I needed to cut a hole in the top shelf for the fan to poke through. Unfortunately one of the four screw holes doesn’t pass through the top shelf as there was already a hole there from existing cables to pass through. But with the other 3 in place the power supply has a tight fit. There are barely a couple of millimetres between the power supply and the top of the case.