Today, I spent a few hours modding the PSU in my (currently) spare MDD. It's a single 1.25Ghz tha I plan to upgrade to dual 1.33Ghz in the not too distant future. So, the upgrade... I removed the front and rear screws from PSU, slid it out, and began unscrewing the top. One side was easy, the other was a pain in the butt, so I unplugged the main plug from the bother board for some more slack and finished taking off the top. I unplugged the fans, unplugged the main power socket, and jiggled the cover free. Unscrewed the earth. Removed the cover. Removed the old fans (Nidec TA225DC). Cut out the flat stamped crosshairs finger guards with a dermal. They didn't look good for smooth airflow. Then smoothed off the rough edge, also with the Dermal. I used superglue to protect the cut edges from corrosion, I could have used paint, but superglue was what was to hand, and I was feeling impatient. The fans I used were the tried and tested (but not very imaginative) Everflow F126025DH, form the Thermaltake Volcano 5 heat sink. I fitted them using silicone rubber anti-vibration pins, I fitted the wire finger guards that came with the fans, also with the same pins. Some creativity was required, as the fans were only held in with 3 screws, not 4. Oddly, the late PSU didn't have any of the noise isolation rubber corner pads on the fans, so I raided an early, pre Apple noise kit PSU I had on the shelf. Very pleased with myself, I tested it to make sure it was blowing air the right way. It was. I began reassembling the PSU, got frustrated and annoyed that I now didn't seam to have anywhere as much slack on the PSU as I'd had earlier, so stripped out the optical drive cage, both hard drive cages, and the 120mm fan. Slack! PSU reassembled, with a little jiggling (earth wires put up a fight). Reassembled the mac, fired it up, definitely quieter, and very definitely way, way, way quieter than the un-quietened noise maker MDD that I'm using now! Next on the to do list... 120mm fan swap for a SilenX IXP-76-14 120x120x38mm (14db 90cfm) Addition of Fractal Design Silent Series R3 fans. 1x 60mm, plus 1x 80mm. CPU swap. SATA card. 256Gb SATA SSD install. 1Tb SATA HD install (I have 4 I could install). Graphics card upgrade. Swap over to be my main mac.