Silencing a P4-1.6A oc'd to 2GHz

Do-It-Yourself Systems
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Case Preparations

I usually opt to maximize ventilation in a solid, heavy case and add sound damping to the interior. But this time, I used a cheap, flimsy generic mid-tower (18" high) ATX case for 3 reasons:

  • I wanted to see if a cheap case could be made quiet
  • I wanted something I could cut up without feeling bad if things didn't work out.
  • It happened to be kicking around in the basement.

With a flimsy case, solidity and thickness went out the window. Improved ventilation for better and quieter airflow was definitely achievable, however.

Out came the power drill, jigsaw and the metal cutting blade. The photos below are self-explanatory. The back panel fan "grill" was cut away to improve airflow and reduce air turbulence noise. The hole in the top panel was made as a "convection outlet" for the PSU. I planned try to run the PSU without any fan, mounting it upside down so that the hole for the second inside fan would be facing up. More on this later.

The grill material for the front panel fan was also removed. I wasn't sure I would use a front fan, but the enlarged air passage hole would help airflow and reduce turbulence. But cutting the metalwork away would do only half the job, because the outside air-in duct is actually a small slot opening at the bottom of the front plastic bezel. So the next step was to enlarge the opening on the front bezel.

Cutting through plastic with a jigsaw is amusing. The plastic cuts easily, but also begins to melt as the blade heats up. Then you have to quickly bend the plastic away from the cut so it won't bond back together as it dries.

Fanless PSU?

Both fans were removed from the PSU before installation in the case. As mentioned earlier, the PSU was mounted upside down. This configuration places the PCB in the PSU at the bottom, and convection can now occur naturally from the unblocked heatsinks. The cover was left off so that the air from within the case would easily rise up around the sides of the PSU and exit through the hole at the top or at the back of the PSU.

On the right photo above, note the green insulated wire being used to secure the PSU in place. With the cover off, the PSU lacks the rigidity to be held properly by just the 4 normal screws on the back panel. The CPU HSF is visible just below it, and to the left, a Panaflo 80mm fan on the back panel, mounted the wrong way here -- it was meant to draw cool air into the hot area around the CPU and the Northbridge chip, then rise up and our through the hole above the PSU.

Later, I changed my mind about the effectiveness of the back panel Panaflow and repositioned it over the video card and the Northbridge chip, as both appeared to get quite hot. (See the photo below.) They benefited considerably from the added cooling. I believe system stability was improved by this fan.

NOTE the metal piece used to suspend the fan over the chip and the video card. It's a PCI slot cover that gets taken off the back of any case whenever you use a slot. Modified with a hole drilled at one end for the single screw that holds the fan. A little bending, and twisting, and then tightening of the screws is all that's needed. My poor man's Zalman-style fan bracket.

Below is a final shot before the front bezel was installed.



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