mcb0
JUAN IS RIGHT. you dn't have to remove the motherboard or even back panel.
you can remove the case switch and speaker, loosen the back panel at the PSU side and open it out a bit, then slide the PSU to the back of the case and lift it up and free.
getting the speaker out is not easy. there's the front and top screws, then slide it around and sideways. I bent up the case bit that gets i the way and cut it off when the psu was out - not drastic.