The silver ducting is from a portable air con unit designed to stop the multi-million dollar machines overheat. The PSU fan on the PC pictured failed, and instead of replacing it, this baby kludge was born from momma kludge to duct cold air into the back of the case.
The CPU fan on my computer broke. The screw holes of the replacement fan did not match up with the old screw holes in the heat sink (there were notches cut out of the corners, there was nowhere to screw the new fan to). I had to find a way to make my own screw holes for the fan, without impeding air flow.