Ducts - The Cheap Cooling Solution

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CPU duct “How-To” – Tony

Ed Note: Tony added more details in this Forum thread.


As all of us AMD owners know, heat is a killer – not only of our processors, but also of our joy in overclocking them. As many before me, I also installed cardboard tunnels to get direct airflow to my heatsink. I never really figured they did much, but I was certain they did lower the processor’s temperature.

However the tape and the agony of this “hack work” never seemed worth its appearance, so I never really did any tests with the ducting idea.

With this basic knowledge in the back of my mind, I set off to build my current dual XP1800 system. I was, as you can guess, concerned about heat well before my motherboard and processors arrived.

I looked at options and started to purchases items I would need to cool it. My first decision was the SK6 and Delta 60mm 38cfm screamers. As more and more items showed up, I concentrated totally on my temps and what I might do to keep them at a good level.

I installed 80mm case fans, 2 up and 2 down. I routed all cables and wires behind my motherboard so there was absolutely no air flow obstruction across the board and its components. I ensured my intake fans blew directly upon the board and threw a third intake in the case front.

I booted her up and let it sit in BIOS for 15 minutes while I had a smoke. I was amazed to see it at 47C. Now this was a disappointment! I removed the heatsinks, reapplied Arctic Silver in a very thin, even coat and did all the suggested things. Yet, still she sat at 47C.

I began to think I needed better air flow with more case fans or I needed the heat sinks to draw room air directly. I decided this time Home Depot needed my money and I needed their ideas. So off to the HD I went, Delta 38 in one hand other hand on my wallet.

Items I purchased:

  • One hole saw, 2 5/8″ for a standard drill: $10.70
  • 2 PVC pipe reducers 3½ – 3″, 4.5″ long: $ 2.99 ea
  • 4 small L brackets and metal screws:      $ 5.99
  • 1 Roll of duct tape:                                      $ 2.99

I returned home and now had to locate the processors’ position onto the case side. As a novice, this was hard for me to do. I pondered this, because the case side is solid steel you can’t see through it to locate the needed holes – you can’t reach into the case to mark the locations.

Then I realized I needed 4 measurements:

  • Top of enclosure to center of fan
  • Bottom to center
  • Bottom to right
  • Left to center

These measurements start where the case side fits onto the main case, not the true top or bottom of the case.

This being done, I drilled the case side, fitted the 2 PVC connectors together and fastened them to the side with 4 L brackets and metal screws. This is important – the PVC reducers are to be installed, large end in, small end attached to the case side.

This is so cases that have sides which slide to close have the room to do so without hitting the heat sink and fan. Also, the PVC does not need to sit right on the fan – it simply needs to cover the fan, but not go so deep as to go beyond the fan itself and cover the heat sink. Check the depth of these adapters carefully.


Also, the PVC reducer is larger around than a 60mm fan by at least a ¼”; this is necessary so the case side will install properly without hitting the heatsink. You also need to ensure the case has good airflow from bottom to top – I used standard 80mm case fans, 3 intake and 2 exhaust.

I booted to the BIOS again and waited like a dad expecting his newborn, cig in hand, pacing. Twenty minutes later, I braved my first look at the temps and smiled wide – I had reduced my temps to 39C!

That was a week ago, and today my system remains at the 39C. I tested it with SiSandra 2002 and let it cycle for a full hour – it never broke 39C. I also removed all my duct tape and installed Radio Shack spiral conduit, added lengths of wires to the case door, converted the case fans to 4 prong adapters and painted it all up. These last details I consider my victory dance.

My total investment including {2} SK6 sinks radio shack and Home Depot:

  • Two Heat sinks: $80.00
  • Radio Shack:     $ 8.50
  • Home Depot:    $25.00
  • 5 80mm fans:    $35.00
  • 5 grills:               $10.00

Total cooling system: $158.50

But remember: I have 2 heatsinks, so reduce this by $40 for a single processor system and remove 1 PVC adapter – $2.99. You will be out $113.50 and cool better than 90 percent of air-cooled systems out there and not have to worry about water damage.

Also, if the noise of extreme cooling is of concern, I suggest using a quieter heatsink fan and having a little higher CPU temp.

Here it is finished:




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