I found a 5-port Linksys networking switch in the garbage a long time ago. After testing it, I discovered the reason it was in the garbage is because it was half dead, only ports 1, 2, and 3 worked and it overheated BAD. I didn't have a reason to use it too much back then so it sat in storage for a few years.
After reorganizing my room about 2 months ago, I decided to use it for my entertainment center so I'd only have one networking wire running to it. I knew it overheated and I wanted to do something about it so it would be less likely to die on me, so I put a fan on it xD
I started by looking for a fan that would be a good size to attach to the top, and I found an old 12V PC fan that was about 1.25 inch diameter. I thought about powering it next, the AC adapter for the switch only put out 7.5V so I wasn't sure about using it. I knew from a previous experience that 12V fans need to be push-started at 6V, and I didn't want to worry about push-starting the fan. I did a test by connecting the wires of the fan to the AC adapter and it worked fine without push-starting!
I decided to go ahead and power it from the same power supply by attaching the fan power to the power plug on the board of the switch, I wedged one wire between the plug and the strip that ran to the board, and wrapped the other wire around the start of a coil (since I couldn't wedge it like I did on the other one). I plugged it in for a test and everything worked fine, so I hot-glued everything in place and started on the case mod.
I needed a good sized hole in the top for the fan to pump air into, and I also needed a well-placed outlet hole to make the air go over the tiny heat-sink on the overheating chip. I made the holes by drilling small holes close together and then rocking my razor blade knife back and forth until it went thru. I also drilled some screw holes to hold the fan down and made a notch for the fan wires.
After putting everything back together, this is what I ended up with:
It runs perfectly with no overheating whatsoever! And I played Halo 3 over Xbox Live thru it no problem.
The fan does work, see :P
I have since retired it and started using a 8-port 3com switch my Dad brought home from work, they were throwing it out too, but there's nothing wrong with it xD I may need the Linksys again someday, but until then it will sit in storage waiting to be used as it did before it had a fan.