So I finally found an air deflector for my Power Mac G5, I tried to play the 2 videos mentioned here, both of them play smoothly in VLC with just one problem, noise. The noise become quite noticeable (but still quieter than w/o air deflector) when I play a 1080p video, the fans ramp up even during lightweight tasks like finder generating thumbnails for files. This video shows a 1.8 DP G5 playing 1080p videos, the machine used in the video remains silent all the time. Then I booted into ASD 2.5.7 and attempted to run a thermal calibration, the calibrate button was grayed out with something like "no calibration needed". Now I don't know if the noise actually comes from aging fans, or if there's something wrong with my G5?