This page is for
reference purposes only. Please use at your own risk. I have
no idea if this change will affect your Apple warranty.
Hopefully, if you are reading this page, you have already recorded and analyzed your Power Mac noise.
The power supply fan insert will help if you are seeing an excess
amount of noise in the 120Hz range. If your analysis shows your
problems to be elsewhere, this may be just a lot of extra work.
Make sure to save your recording so that you can do another
analysis after the change and see how much difference it made.
Getting started
You will need the following tools:
Torx 10 screwdriver (or 2.5mm hex key I am told)
Phillips screwdriver (not sure of size, bring a few)
Removing Power Supply screw
First remove the power plug at the rear of the case. I would also
suggest removing all other cables from your Power Mac. You can
leave them in if you want, but you could accidentily yank down your
monitor or bend a cable if you don't. Turn the Power Mac around so
that you are facing the rear. Slowly and carefully, use your Torx
10 screwdriver or 2.5mm hex key to remove the screw holding the power
supply. Don't try too hard. I stripped the screw on my first
Power Mac and it required a screw extractor kit to remove it!
Opening the Case
Turn the case around so that you are facing the front.
Place it on it's left side.
Pull up on the handle to open.
Swing the case around to the
right.
Facing case
Looking from top
Removing the Optical Drive Cage
The optical drive cage sits on top of the power supply cables.
You will need to remove the optical drive cage to free up the
power supply.
Slide up the optical drive wire cover on the left side of the
cage.
Remove the IDE cable (the thin wide one) and optionally the power
cable. The power cable is harder to remove and can be left in.
Remove the two screws holding the optical drive cage.
Slide the optical drive cage to the left and then up.
Flip the drive cage around 180 degrees horizontally so that it
faces left instead of right. You should be able to set it down on
it's face as shown below.
Removing the Power Supply
Ok, looking into the case, the first thing right in front of you is the
power supply.
Use a Phillips screwdriver to remove the screw holding in the power
supply. Now, slide the power supply to the right about an inch or
so. It will take some force. Do it slowly and gently though.
You should be able to set it down on top of the hard drive cage as
shown below. Turn it so that the bottom of the power supply and
its fans are visible.
Placing the Insert
The previous picture shows the dark area where the 60mm power supply
fans are not covered by the power supply. Thus, the power supply
fans come into direct contact with the case. On both of my Power
Mac's, this caused a fair amount of vibration in the 120Hz range.
Now place some type of dampening material over the exposed area of
the power supply fans and just this area. Obviously, do not cover the circular intake
area on the right where the air comes in! You can see the
dampening material that I used from an old Palm Pilot case. Make
sure whatever you choose is not too thick. Otherwise, you will
have a problem sliding the power supply back in.
Reassembling
You may have to hold the dampening material in place while you slide
the power supply back in. It will be a bit harder to slide the
power supply back in. If you run into resistance, first press down
firmly on the right side of the power supply directly over the fans.
If that still doesn't do it, try pressing down on the left side of
the power supply fan. On my Power Mac's, I found that the left
side had to tilt down slightly to slide back in. In either case,
take your time, jiggle it around. Eventually, it will go in.
Just don't force it in. If you really get in a jam, take the
insert material back out. Jiggle the power supply until you figure
out what it takes to slide back in. Then try again with the
insert.
At this point, you can just reverse the entire procedure.
Reinstall all of your cables, and lastly the power cable.
Power it up and verify that air is still coming out of the rear.
Re-analyze the noise from your Power Mac using Amadeus.
Report your results to the Yahoo G4Noise group.
Case Fan Insert
Incidentally, I ended up using another piece of the Palm Pilot case to
cover the area where that huge 120mm case fan touches the bottom of the
case. I started hearing vibrations from there occasionally.
I don't have pictures, but once you remove the optical drive cage,
you should easily be able to slide out the 120mm case fan. You
can't miss it! Plus, there are no screws holding it in. If
you have some extra material, it probably wouldn't hurt to do it as well.
