G4 Quietsilver Fan & LCD Mod

by Swordfish


What started as an experiment on how to cut the noise back has resulted into a mildly tricked-out Mac with all new case fans, a fan-failure warning siren, and an LCD temp monitor on the front. Here's how:

For the longest time, I'm been wondering where the noise in my G4 comes from, and if I can make it quieter.

All you have to do to figure out what's noisy is open your case up and start selectively unplugging stuff before turning on the main power: Temporarily disconnect the CPU fan. Try the big case fan. Maybe it's the hard drive that's noisiest? You won't hurt anything as long as you do this for short amounts of time.

There's lots of bad advice online about how to do this, so I wanted to post real info on what works:

The LCD temp monitor: Why? When you start experimenting with "under-cooling" to cut noise, you need to make sure you're not frying your CPU. I found a product called the CompuNurse at bigfootcomputers.com.


The CompuNurse just hooks up to a spare Hard Drive power line for power, and allows you to put the temp probe and display anywhere. The internal speaker is crap anyway, so I pulled that out and replaced it with the LCD, mounted to a piece of black bristol board.

Use some silver 3M adhesive sign vinyl to cover the beige front of the CompuNurse to give it that "Factory" look where it shows through the speaker hole. Don't centre the LCD - you need to see the right edge of it, and that's all you have room for anyway (see top image).

I re-routed the speaker to sit on top of the optical drive...


Cut a hole in the bristol board to fit the LCD...


And placed the temp probe on the heatsink.


While you're in there, you might as well clean up those cables with some split-loom wrap and zip ties.


DONE! Now that you can monitor the CPU temp, you can find a balance between noise and heat. This is a good idea.

The 60mm Fan: Wow - this one is easy. I ordered a Panaflo 60mm "Low" fan. The only weird thing is that the Mac has a 2-pin connector and everything else in the world is a 3-pin. You could cut / splice the stock connector off the old fan onto the new one (smart), but what I did was try to force the new one to fit on (somewhat stupid). Match the positive (+) and negative (-) wire on the new one with the old one. I forced these two to work instead of splicing wires, resulting in a broken retaining clip on the motherboard side. Problem? No problem - just secure it with a small zip tie.



The 120mm Fan: Somewhere online it was said that the main fan was probably the noisiest problem and that you should replace it with a Panaflo L1A fan. Too bad the stock fan is 25mm deep, and the Panaflo is 38mm. The air pushed by the 120mm fan needs to make a right-angle turn to get out of the case. So while the L1A series fans are very quiet and good performers they are too deep for the fan bracket - resulting in air bouncing back into the case instead of being exhausted like it's supposed to do. So I shopped around...


Evercool 120mm Aluminum Case Fan - 2000rpm, 79.14cfm of air, <30dba noise. Pushes TONS of air, at high RPM. Looks great and reasonably quiet, but it's just too much cooling for what you need.

Vantec Stealth 120mm - 1500rpm, 53cfm, <28dba (supposedly). Well ya, it's the right size, and maybe it is technically quieter, but the airflow is much lower, and when it spins up there is a definate "note" or tone like a tiny air-raid siren. No thanks.

(Note: One Dba makes a difference: 30Dba is twice as loud as 29Dba.)

SOLUTION? Slow down the Evercool. Get either an "Alpha and Omega Computer Fan Speed Controller w/ Fan Alarm" or an "Evercool DC Fan Speed Controller SCB-A ". The first one (which I am using) is cool because it has a built-in warning siren that let's you know if the fan that it's connected to has failed. The second one is cool because it mounts to a spare PCI slot so that you can adjust speed without opening the case. These items are great for adjusting airflow to protect your CPU on a hot day.


Isn't that big Evercool fan sweet? The red stuff behind the fan is an adhesive film I used to cover the holes in the case. Maybe they're for some kind of brilliant turbulence or back-pressure (?), but I think all they do is give the air a place to go that isn't out of the case. I'm not one to second guess Jonathan Ive, but I find that my case temp is a few decimal points lower with the holes covered.


The 120mm fan mounts to the bracket with 4 screws, and the bracket mounts to the case with 2 screws. You can take the fan bracket on & off without removing any other components. Lining the lip of the bracket with felt and filling the gaps around the fan with foam will cut noise too.

I also used some extra foam in front of the power supply to hopefully suck up a little noise and to give air a more direct flow from the CPU intake to the power supply / 120mm fan exhaust. *Make sure it doesn't get in the way of the case latch.* The other foam I put above that noisy IBM hard-drive (leave some room above the drive for airflow if you do this).


Finally, I found a backlit version of the temp monitor LCD! This is *REALLY* hard to find, but the same as the CompuNurse to install. It's way better than keeping a flashlight around to read the temp.


Next: A couple of nice quiet Seagate Baracuda V series 80Gb Hard Drives (very quiet), some Dynamat or Akasa Pax Mate for noise insulation, and maybe some Vantec noise dampening kits for the powersupply and the 120mm fan mounts. If I go insane I might buy a replacement G4 power supply and swap out the stock fans in it with some better quieter ones.

Good luck - hope this info helps somebody. Keep on Moddin'!

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