• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

Duct Your CPU Fan!

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.


Dec 23, 2000
I always thought that cpu fans were a little inefficient since the air coming off the HS gets sucked by the fan right back onto the HS,so I tried something.

I took a cardboard papertowel roll and put 4 slits in the end to fold over as tabs.I then screwed those tabs onto the fan intake.

It now gets it's air about a foot from the HS(I've been running an open case for awhile).

The cpu temp went from 43c/48c idle/load to 38c/43c. A 5c drop for no cost.When I get some supplies I'll make a permanent setup.

Any ideas?
I already did the same thing, take a look at the picture. alum dust works great and is cheap.
hi JetJam.

I took a look at your home page, and it looks pretty cool. What I want to know now is:

1) How far does the duct overlap your orb, and how much of it remains uncovered?

2)How did you attach the duct to the fan?

I also have made a CPU duct. and some other case adjustments. I am going to post some pic's in a bit. here are my temps
case @ idle = 20c
CPU @ Idle = 25c
CPU @ full load = 30c

Here are my spects:

Abit KT7-Raid (WW Bios)
VIA 4.26 4-1
AMD Athlon 1.0 Ghz
2 128mb Mushkin Rev.2 PC133
Herc GeForce2 MX 32mb (Tweaked for OC'ing)
Herc 6.34 Drivers
3com fast ethernet 10/100 Nic
SB Live w/Cambridge Surround sound Speakers
2 Seagate 4gig 5400rpm (on raid "striped") OS
Maxtor 10gig 5400rpm
WD 10gig 5400rpm
52x creative CDR
2 case fans (in/out 80mm)
FOP-38 7000rpm HSF
air duct (directly to the chip)
Customised cutout case
300W Power supply
Win2k Pro
the duct sits just on the top, you don't want to go around the side to much that would stop air flow.
the duct can easily be cut to fit even at angle's if needed.
Great idea but do you really need the external fan on the case and the cpu fan pulling in more air?
Great work JetJam. Visited your homepage. Excellent Case mod and cable routing ! A guy could wind-surf in there! :cool:
Super idea, as a less than extreme version that might take a minute to throw together, you use a 3" tube and fasten on top of the fan like JetJam mentioned so as to block any heat from the sides. You get much cooler air right to the fan.
yog (Feb 09, 2001 09:02 p.m.):
Great idea but do you really need the external fan on the case and the cpu fan pulling in more air?

Which fan are you refurring to?, side(on case) duct fan helps force air into heatsink and it does help.
front case fan helps bring cool air across board, with out it my board temps rise 10f degrees.
How about this?
Athlon 1bird 800 at 1gHz on an ASUS A7V
CPU temperature before tube in idle: 52°C
with tube: 45°C !
Easy to set up ( took me 15 minutes), cheap materials, no case mods.
Your setup with the ductwork has an obviose affect on your processor. But I am wondering if this creats other problems with your board and video card as now they are not getting air blown to them and having that big air duct running through your case blocks air movement. Did you check to see if your board temp rose at all doing this?