I mentioned last week that I ordered a dual 1.33 GHz CPU module for my MDD G4. The new CPU was pulled from a G4 Xserve – it has 2MB of L3 and requires a 167 MHz frontside bus to work at its full clock speed. It arrived today so I thought I’d document the upgrade process for anybody else wanting to upgrade their MDD G4. This particular G4 happens to have the slower 133 MHz FSB – it originally shipped with a single 1 GHz module and is one of the FW800 models. Fortunately, it is fairly simple to change the bus speed on the MDD boards – you just need to remove a resistor on the underside of the board. 1. Remove all cards, cables and the single screw securing the logic board to the case (it’s near the little fan in the door). I also removed the backup battery. Slide the logic board away from the back of the case and remove it. 2. Locate and remove the resistor marked R676 on the underside of the board – it’s near the heatsink under the CPU area. (see photos) You’ll need a fine pencil-tip soldering iron. Make sure that the removed resistor doesn’t get lost somewhere on the board! I didn’t find this too difficult as I do a lot of work with electronics, but if you don’t have experience with SMD components, practice loads on some old PCBs first. 3. Reinstall all components back in the case and reattach any cables. Remember to reapply thermal paste on the CPU module before putting the heatsink back on. This upgrade gave me a huge increase in system performance. There is now absolutely no slowdown anywhere in the Leopard UI. YouView can now play 720p HD videos quite happily, Flash Player is now able to play full-framerate full-screen SD video in all of the websites I tried it with. Games are now running so smooth, it's just great.