This week I decided to do some work on the home computer. Ever since I built the computer, I’ve always thought that it ran a little too noisily, so I decided to try to figure out what was causing all the noise. Earlier, I had already replaced one of the case fans with a silent running Panaflo L1A fan. This fan produces about 21 dB of sound when measured at one meter. 21 dB is about the amount of sound you would hear when someone is whispering five feet away, so this fan is pretty good for making a computer quieter. It wasn’t enough though. When I was working on this, it was clear that the noisiest part of the computer was the fan that sat on top of the CPU heatsink.

When computer components overheat, they fail, and the part of the computer that generates the most heat is the CPU. The most common method of cooling a CPU is putting a piece of metal on top of it to conduct the heat away. The piece of metal has a lot of surface area, and one then attaches a fan on top to blow air across all of that surface area. The piece of metal is called a heatsink, and the heatsink and fan are collectively known as the HSF. When we purchased the AMD Athlon XP processor for this computer, we decided to just use the HSF that AMD provided. Now, over a year later, we’re finally replacing it to hopefully make the computer a little quieter.

The first step of this project was to disconnect everything from the computer (especially the power), and open it up. Luckily, the Enlight 7237 case that we use for the home computer is very easy to open. The front panel pops off, and one thumbscrew holds the side panel in place.

As you can see, there is a big tangle of wires inside the computer. I had plans for dealing with those as well. The main focus right now was the larger of the two black fans in the picture. That’s the one that is sitting on top of the CPU heatsink. I was originally hoping to replace just that fan, but the fan is a 60 mm fan, and I couldn’t find a quiet 60 mm fan that could blow as much air as the original. I decided that we needed a bigger, quieter fan (like the Panaflo L1a), but this meant that we needed to replace the heatsink as well. Removing the fan and heatsink was just a matter of removing a few screws for the fan, and unclipping the heatsink from the motherboard.

Here is a picture of the CPU after the HSF have been removed. There is a bit of crusty residue left behind around the CPU. Neither the surface of the CPU nor the surface of the heatsink are completely flat, but they are pretty good. To improve how well heat transfers from the CPU to the heatsink, a paste is applied to the CPU. This paste makes sure that there are no tiny gaps between the CPU and heatsink, but it also leaves behind this residue. I wasn’t concerned with the residue around the CPU. That residue wouldn’t interfere with the new heatsink, but I did want to clean off any residue directly on the CPU. Some rubbing alcohol did the trick. Instructions clearly stated that rubbing alcohol was the cleaner of choice in this case because it evaporates with no residue of its own.

The new heatsink we’re going to use is the Thermalright 900A. This heatsink has gotten great reviews. It has a lot of surface area, and it’s made of copper which conducts heat very well. The heatsink is also relatively inexpensive as compared with other top-of-the-line CPU heatsinks. We got it for $20 from The other nice thing about this heatsink is that many different sizes of fans can be attached to it. The Panaflo L1A should attach nicely.

At this point, I was being careful not to touch either the bottom of the heatsink nor the CPU with my bare skin. The oil from a person’s skin can also leave a residue that will interfere with the heat transfer from the CPU to the heatsink. I decided I should wear some latex gloves, but unfortunately, the only ones I could find are these bright purple gloves.

I applied a thin layer of thermal paste to the cleaned CPU and then attached the heatsink.

The fan clipped right on top of it.

Finally, before closing up the case, I decided that the ribbon cables connecting the CD-RW drive, the DVD drive, the floppy and the two hard drives were probably obstructing the flow of air in the case. They also contributed to the big tangle of cables that we saw when we first opened the case. I bought some rounded cables to replace the ribbon cables.

I think the final result is a case that is at least a little neater inside. I closed up the computer and plugged all of the peripherals back in. It was quieter at least. I turned it on and ran some tests for a couple of hours to see if the CPU would overheat. If I didn’t have the heatsink on correctly, I would expect to see CPU temperatures higher than the normal 130o F that I see after the computer has been on for a while. After exercising the computer for a while (using a distributed computing program that uses all available CPU power), I checked the CPU temperature. It was 110o F. So, I ended up with a quieter and cooler computer at the same time.

Now the computer isn’t quite quiet yet. The last thing that seems to be making any significant noise is the fan in the power supply. I have one more Panaflo L1A fan that I can possibly use to replace the fan in the power supply. The next time I feel like opening up the computer, I may consider replacing that fan. The only problem is that power supplies have all sorts of warnings on them about opening them up, so that probably isn’t a good idea. The safest thing to do is to do some shopping for a nice, quiet power supply and replace the whole thing. Oh well, that’s a project for another day.