More sound proofing material is used on the inside of the case as well. Both side panels and the top of the case have sound dampening material factory installed. There also appears to be a rubber seal all the way around the face of the case where it attaches to the frame work. This effort to kill any annoying sounds your computer may make isn't very well advertised on any retail site. Although they call this a silent enclosure, Lian Li's home page shows nothing about their efforts to kill noise.

Sound dampening material installed in the top of the enclosure.

     One of the brilliant features of the PC-6070 is the tool free removable motherboard tray. 4 thumb screws is all that hold the tray in. Remove the screws and the tray slides out with no effort what so ever. This is one thing I have always loved about Lian Li cases. Installing and removing a motherboard has never been so easy!