Casemodding - Making an Apple Quicksilver G4 800Mhz quiet!

Ok, I have a PowerMac G4. It is full of energy and makes a lot of noice. The more you think of it, the more annoying it gets. I finally had enough, and started doing something about it. This tiny article covers my wherabouts.

I started with identifying the source of the noice. In a Quicksilver such as mine, there are four possible sources of noise, namely:
  1. Power Supply Unit (PSU)
  2. CPU Fan
  3. Chassi Fan
  4. Hard Diskdrive (HDD)
The most obvious way to remove any sound they make is to remove the component it self. Could that be done ? Well, for the PSU, thats a negative. Though, what really makes the noice is a fan. I'll be back to the PSU in  a while. Secondly, the CPU fan. Since an 800Mhz G4 generates some heat, I cannot rely entirely on passive cooling, so it  had to stay there. The chassi fan on the other hand could most likely be removed. Finally, I had to do something about the HDD noise. This is how I did it.

1) Power supply unit
Apple uses a rather special PSU, so you cant just go buy a "quiet" one and be happy. Apple has for some reason also a +25V output. Instead I had to do something about the current one. Now, how bad was the current? By stopping the fan while the Mac was running, I realize this fan was really bad. It just had to be replaced (bye bye warranty :-)

First thing, noise is air not flowing correctly, thus generating vibrations, buzz. Looking at the back of the Mac, I saw there was a redundancy in protection. There were two separate protection bars keeping fingers out of the fan. One had to go.

This picture shows what I mean, even when I removed the first protection, the Mac chassi had another. No need for both. (sorry about the bad image focus though :-) Still I had to replace the fan. I removed the PSU from the chassi, and opened it up. Note : PSUs contains high voltage even when unplugged, dont touch it unless you know what you're doing! Now have a look at these pictures...

I removed the current fan from the PSU, and replaced it with a PAPST fan instead. Here they are...

Now I just had to reassemble the PSU, the final product looks like this.

See, no protecting metal, but the Mac chassi has an extra anyway. Less noise, less hindering materials, better cooling. All's well :-)

The next step was to do something about the HDD. In its current state it was actually rather quiet, but lets see what can be done anyway. I took three things into consideration. First, it was to be isolated from the metal casing, so that vibrations from the disk did not spread through the chassi. Secondly, I wanted to isolate it as much as possible, and finally, I had to make sure it wasn't getting too hot.

These pictures somehow shows the idea. I used insulation on the sides, so the HDD is not screwed onto the chassi, but rather squeezed in between. Below and on top, I placed a layer of Magic Fleece (tm). I dont really know how much this did, but sure it didn't hurt. Also note, there is a hole on top of HDDs (atleast this one from IBM) saying "Dont cover this hole".... dont ....I guess its for ventilation or something.

Moving on to the CPU cooling and the 6 cm fan. The standard configuration for the fan is to blow cool air from the outside onto the heatsink. No real point changing this, since the CPU is a rather critical component. Apple has already put some effort into this, the fan is not attached directly to the metal casing, but rather onto a rubber thingy. The problem with this rubber holder is that it does not cover the fan completely, so the air is not taken from the outside, but from the inside instead. Rather stupid construction, but easilly fixed.

I simply isolated the rubber holder, so that it could not get it's air from the inside anymore. That stopped some annoying whizzling sound, and also improved cooling a little.

Finally I attacked the chassi fan, a large 12cm fan positioned in a really really stupid way. It pushes air straight into the side of the chassi. (Ok, there are a few holes, but what the heck was Apple thinking ?). My guess is that this fan is there to support Mac configurations where you fill up the PCI slots, and loading it full of HDDs and stuff. Since my Mac is almost empty, I figured this was overkill.

First of all, i cut away the metal protecting the fan from any fingers. I dont intend to open the box that often anyway. Next, the fan is by default sucking out air from the case. Since that makes two out (psu + chassi) and only one in (cpu) it's an unbalanced equation. And, always strive towards more in than out. So, i simply rotated the fan. It now pushes cold air into the box, onto the passively cooled GFX (Radeon 7500).

Now to the final twist.. a 12 cm fan makes quite some noise. I made an ugly hack and attached the fan to 7V instead of 12V. This will of course reduce both noise and volume of air moved. My ugly hack was to take the Red and Black cables from the fan and attach them to +12V and +5V on a standard Molex connector. I used some tape to keep the cable in position.

At this point, tightened all screws and closed the box, and pushed the power button. And to my great pleasure, the box was almost completely quiet. Total success ! :-)

Just a few final words.. The most critical component was the PSU.. You definitely want to do something about that. And keep in mind, you get what you pay for. An 8 cm PAPST fan cost about  $ 12, but it is well spent. "Quality remains while the price is forgotten", as someone said.

Hope you enjoyed the reading, drop me a line if you have any comments.