Heat and noise are two large issues facing many Quicksilver (and other) G4 owners. I found my quicksilver to be a little noisy for my taste, and much too hot. I thought that replacing the fan in the power supply (PSU) and removing the (somewhat redundant) finger guards would decrease the PSU's echo capacity and allow more air to be circulated at the same sound volume, with some hope of a more pleasant noise. For this project, I won an additional power supply on ebay, and bought a very well designed case fan from ThermalTake called the Smart Case Fan II. I cut the fan grilles off using a Dremel High RPM tool with a cutting wheel and a grinder. I have seen other work where others have removed the grilles with metal sheers (1,2,3) I don't have access to an appropriate set, and the gnarled metal looks unprofessional. For more information, XLR8yourmac, DualG4.cm, and, of course, Google. I appologize about the poor picture quality. I have a very old digital camera, and it doesn't do a very good job. Thus, most of the enlarged pictures are very grainy.
 | As I said earlier, the temperatures in my mac were a little high. In this photo, you can see the internal temperature of the G4 was roughly twice the temperature of the surrounding environment. This is much warmer than the average PC, or any of the older Macs i have access to ever get. The major goal of my fan swap was to lower this temperature a bit. (I don't have access to a thermocouple gauge at the moment... so all ~current~ observations below are qualitative in nature.) |
 
  | Here's some pictures of my starting materials: The new, unchanged power supply, it's label, and the new fan. I set up the fan, which comes with the option of manual speed control, thermal heat control from a provided thermister, and normal (unregulated) fan mode. I opted to use the manual speed control to set the fan to match the flow of the original fan at full capacity. The fan built into the PSU is speed controlled by external circuitry, so the equipment (deigned for CPU temperature monitoring) was not needed. I originally planned to power the fan from the original fan power feed, but the increased draw from the new fan required and external connection. The old fan drew about .24 Amps while this fan can draw in excess of .7 Amps. Note that little yellow sticker in the upper right corner of the power supply label. They aren't kidding. |
  | After initially removing the top of the power supply, This is what I saw. The power-supply is liberally re-enforced with glue to protect the components from shocks. The main power feeds are glued to the fan in 2 places, which had to be pried free in order to remove it. It is also interesting that the speed control for the fan is not handled by the fan itself (as the rest of the fans in the system are). The fan is connected to a daughterboard, which then varies the voltage based of an external temperature sensor attached to a heat sink. (If anybody knows why this external control is used, please email me.) |
 | This picture shows the PSU after the fan has been removed. You can now see clearly the wires that had to be unglued for it to be removed. I found the easiest way to remove the fan was through the top of the PSU. It wasn't designed to have surgery like this done (i would guess the fan is placed in fairly early in the assembly process), so I had to flex the sheet metal a bit to get a hole large enough to remove it. |
 | After removing the fans, I used a PC to calibrate the new fan to match the output of the old fan at full power. Surprisingly, they are both very quiet outside of the computer. This probably means that the annoying noise the PSU makes is a result of resonance within the computer and air resistance as it flows around grilles and components. |
  | I first cut out the circular finger guard on the front of the power supply. There is already a guard built into the computer case, so it is redundant. These pictures show the rough cut, then after some cleaning up with a grinder. |
 | Next, I then removed the grilles from the back. This process required a great deal of care, as there are many components that are less than 3 mm away from grille lattices. After a lot of cutting and grinding, I achieved the pictured result, without punching a cutting wheel through the side of a capacitor. |
    | Next, I placed the new fan inside the PSU. Once again, the case required a little flexing in order to get the fan in. In these photos, the fan his connected to the internal fan connector of the power supply. I later found that it doesn't supply enough current to spin the fan, so connected it to external 12 volt bus used to power the hard drives. I put the variable resistor that adjusts the fan RPM outside the PSU so i could tweak it if need be. I also had to break the guides on the fan connector so i could plug the fan in. If you have to do this, be sure to mark the polarity of the plug before you break the guide. The pin closest to the fan is positive (Red or +). |
 | In order to remove the power supply from the G4, you have to take out the optical drive and the 3.5 inch device below it, as they share a bracket with the supply, and they block screws to access it. To remove the supply from the back of the case, a 5/64" hex key is required for the screws in back. |
  | Here's a comparison of the old and new power supplies side-by-side. It looks like the removal of the guards increased the free surface area by about 30% on the front, and 40% in the back. Also, the back finger guards keep unsuspecting monkey descendants form sticking their fingers within and electrocuting themselves. After this modification, i highly suggest turning of the machine, unplugging it, and cycling the power button a couple of times to let everything discharge before messing around with the PSU. It really hurts if you don't. |