Building a computer into a desk frame.

[charlesshoults]

I have a reloading table, measuring 60" wide, 33" deep and about 32" tall. The four legs are made from one 2x6 and one 2x4 each. At the table top height, 1x4s are used to join the four legs together. A second set of 1x4s is used to create a platform about 10" from the floor. I plan to expand each, so that they can be enclosed to create 8" high storage cavities, hoping to get rid of a small book case I have in the same room. A portion of the upper cavity will be used to hold a computer, built into the table. The table top is built from a pair of old office desks that my company gave away while remodeling part of the building. I'll be picking up a Mountain Mods motherboard tray and will be looking for methods of keeping the computer dust free.

My first thought is to use positive pressure. The Mountain Mods tray has mounting for a single 120mm fan. That fan, plus the power supply will make up the only exhaust ports. For intake, I'm planning to use 4-6 120mm fans, and on the outside of the fans, hope to use a 20" x 20" paper air filter, pulling air from the bottom of the table top, so shouldn't be able to pick up any standing dust or dog hair (two Labrador Retrievers sleep in the building where the table currently sits). For drives, I'm going to get a 3x5.25" drive bay cage from Mountain Mods and will probably fit it with a four bay SATA cage. The motherboard configuration I'll be using is a 3.2GHz socket 478 P4 and 2GB of ram. Ubuntu or XP Pro? Undecided. My old 19" monitor will be set toward the back of the table and input will be through a wireless keyboard/mouse combo.

Would four intake and two exhaust fans be enough to maintain a positive-pressure system? Probably. A better question might be, is a large air filter going to create too much air restriction for a computer to keep cool?

 

[Power5]

Negative pressure is better for dust control. I really can't picture what this desk looks like right now. Sounds like my desk dimensions, but unfortunately I was only able to fit a 24" depth. Post some pictures of this beast. I love big desks.

 

[bernz]

I don't mean any disrespect, but positive pressure is a hell lot better for dust control than negative pressure. Negative pressure will cause air to enter the case from any possible venue. Positive pressure keeps dust out by intaking air only over filters.

 

[charlesshoults]

The table I have looks like the picture below. The top of the table is in three sections: a 10" wide section that goes across the entire back and two forward sections, split down the middle, allowing for half of the top to be opened at a time. The cavity below the table top is 9" high. The motherboard will go in the back left corner, with the power supply to the right and a wooden wall to the right of it to limit the air space available to the computer. Facing the left, just in front of the motherboard will be the 3x5.25" cage. Just forward of that cage will be a steel midplane, onto which I'll mount the fans. (I could skip the drive cage and for the sake of space, just fit one or two drives) I'm planning on allowing for 20" across, so will need to decide on the number and size of fans, but yeah, as long as the air pressure generated by the intake fans is higher than the air pressure of the exhaust fans, it creates a positive pressure within the computer case, pushing air out of any gaps. As long as all of the intake fans are filtered, very little dust should make it into the case. In front of that midplane, I should be able to fit a 20" x 16" filter, drawing air up through the bottom of the chamber.
The vertical section at the back of the desk will mostly be pegboard for mounting tools and storage bins, but leaving space to mount the LCD monitor on a VESA mount in the center.