by: Larry Mingus Published: November 4, 1998

• Improve cooling
• Reduce dust problem, with positive air flow
• Lower the noise.

In this project I used the Enlight 7237 ATX cabinet, I have had good luck with Enlight and it is one of very few midtowers that have 4 exposed 5 1/4" drive bays. Check the review of the Mobile Rack MR-27 removable drive bay to see why I put so much emphasis on cabinets having 4 exposed 5-1/4" drive bays.

The Enlight 7237 uses two fans, an exhaust fan in the power supply and an intake fan mounted at the bottom front of the case. It has adequate air flow as it comes for cooling, but the power supply fan is more efficient than the front fan, which creates a vacuum inside the cabinet. When this happens air is sucked into the cabinet from every opening, floppy drive's, CD-ROM's, modem phone jacks, etc. This is not a big problem for someone who uses the computer a few hours a day, on the other hand if you rarely shut your system down this is an issue to be concerned about. See computer dust: "Should you worry?".

The following is what I have done so far to address the above issues.

Click on photos for larger images

Removed most of the fan screen metal to increase air flow. Leave enough metal to keep the filter material from being sucked in by the fan. I have no way of measuring the effectiveness of this mod other than my experience with auto racing. One of the tricks for Camaros is to modify the stock air filter by removing 75% of the air filter reinforcement screen. After I cut out all the wires from a Camaro air filter I laid them against each other and it covered 25% of the filter . This however, could be a waist of time in this project. ;) but it can't hurt either.

1/4 inch thick charcoal air conditioner filter is used to reduce dust intake. I am still looking for a better filter solution. This works fine but I want to find a filter material that will allow cleaning and reuse of the filter. It would also be nice to make some type of air filter holder that would eliminate the need for tape.

Above the filter in the 3.5 inch drive bay opening is an additional Radio Shack blower that is used to cool the P2 CPU, the blower not only cools the CPU with cool room air, but also adds positive air flow to the case. The intake for this Radio Shack blower is also filtered to reduce the dust problem.

This is the an inside view of how the Radio Shack blower gets air to the CPU. Check the P2 Ram Air project for more details.

Enlarged the air holes in the front bezel of the Enlight cabinet, the original holes are way to small. I didn't want to drill half inch holes that would look like hell. I may add two or three more rows of holes.

This is the back side of the Enlight bezel the area outlined in blues shows plastic removed to aid in air flow. The whole idea here is to make sure the front fan has as much unrestricted air access as possible.

So far the results are pretty good. The positive pressure air flow is much better than when I started. The test is to hold a piece of paper to the side vent of the Enlight cabinet to see if it gets sucked to the vent holes. At this point I have reduced the negative pressure by about 80%, I have no way to accurately measure this other than the paper test. The problem is, the power supply fan is a lot more efficient than the front fan, if the power supply fan is restricted just a little with my hand the paper falls. Even with the added Radio Shack blower the power supply fan draws more air than both front fans can deliver.

The next experiment that I am going to try is to reduce the speed of the power supply fan just to the point of passing the paper test. It is to loud anyway, so reducing the RPM will help with the noise factor too.

Noise is big on my list of rants, I have three systems in the same room running 24hrs a day. Once in a while I shut them all down, that is when I get on a noise killing rampage. I think I should work for the EPA sound division... <g>. In this project noise has stayed about the same. The added Radio Shack blower is very quiet for the amount of air that it pushes, and whatever noise it added, it's less than what can be heard over the power supply fan.

The dust demon, if you haven't checked your CPU and power supply fans in the last 6 months I suggest that you do. Here in Florida, using a cabinet with negative air pressure is a nightmare. I have worked on a few that I couldn't even recognize the parts in the power supply there was so much dust (less than 1yr in service).

I think the biggest problem is that engineers don't design personal computer cabinets for 24/7 use. Who wants to use an *expensive_big_loud* server cabinet that is truly designed to run non-stop?

Where there is a will, there's a way... ;)

Note: The cooling projects are not over. I am going to continue experimenting and documenting temp changes with various fan arrangements, fans, and dust filters. So, stay tuned for updates.

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