Ducting from CPU fan out the exhaust fan?

DriveEuro · Jan 2, 2003, 12:26 AM

So does it sounds dumb or worthwhile to reverse my CPU fan and have it sucks air through the heatsink and duct it out to my 92mm exhaust case fan? I would use ducting kinda along the lines of Madgoats on his Windtunnel. The whole purpose would be to get that hot air out from my new XP2100 Palamino. Does this seem worthwhile? Does anyone think that it would work?

Mystik · Jan 2, 2003, 01:52 AM

imho, no project is dumb. =P

But, from my experience, having the fan blow onto the heatsink
gives better results. Also, if you just duct it normally, while still
having it blow onto the heatsink, i think it would be better since
it would always be blowing the ambient air outside, rather than
using the air from inside your computer to cool the heatsink..
also, i'm assuming that you have at least another exhaust fan
(not psu).. i think that way would work better.

DriveEuro · Jan 2, 2003, 02:00 AM

1 80mm 2500 intake front of case, 92mm 2500 rpm exhaust below cpu, 42cfm slot exhaust below vid card.... my 60mm 5000 rpm intake on the side of the case died last week.

Mystik · Jan 2, 2003, 02:07 AM

If you want cooler temps, i think blowing onto the HSF with the
duct would be better than blowing out.. since, as i said, it'll always
be taking in cooler air from outside, rather than using the warmer
air from inside your comp..

DriveEuro · Jan 2, 2003, 03:02 AM

Eh...

reno · Jan 2, 2003, 03:04 AM

Just leave it, ducting is overrated, forcing air over a HS cools the damn thing off much faster than sucking air over it. What feels better on a hot day? Blowing a giant air conditioner in your face, or sticking your face by the air conditioner's intake? Common sense.

Matth · Jan 2, 2003, 05:00 PM

Turbulent air forced into a heatink by a close fan, has more effect than the same airflow generated by a fan on an 80-60mm funnel adapter, or the same volume pulled out by the fan.

Blowing in, the flow tends to stick to the fins by bernoulli effect, while drawing out, the inward flow takes the easiest path.

If the heatsink itself is "ducted", in the way that some very close pitch finned ones are, the drawing out MAY be as good as blowing in.

Mystik · Jan 2, 2003, 07:29 PM

Alpha advertises their HSF's to work better when blowing away
from the heatsink.. but when I tried this, my temps increased
by +-3 celcius.. this was on an open case (side panel off)..

I guess your milage may vary?

Jan 2, 2003, 12:26 AM	#1
DriveEuro HardwareHeaven Extreme Member Join Date: Jul 2002 Location: Gurnee Illinois Posts: 4,677 Rep Power: 0	Ducting from CPU fan out the exhaust fan? So does it sounds dumb or worthwhile to reverse my CPU fan and have it sucks air through the heatsink and duct it out to my 92mm exhaust case fan? I would use ducting kinda along the lines of Madgoats on his Windtunnel. The whole purpose would be to get that hot air out from my new XP2100 Palamino. Does this seem worthwhile? Does anyone think that it would work? __________________ [color=orange]ASUS P4P800 Deluxe [color=black]-[/color] 2.4C --> 3300mhz [color=black]-[/color] Mushkin PC3200 at 220 5-2-2-2 (cpu limited) [color=black]-[/color] BBAti 9800Pro at 430/375 [/color] [color=black]3[/color][color=gray]D[/color]M[color=black]a[/color][color=gray]r[/color]k[color=yellow]01[/color] [color=black]3[/color][color=gray]D[/color]M[color=black]a[/color][color=gray]r[/color]k[color=yellow]03[/color] 16001200 12801024

Jan 2, 2003, 01:52 AM	#2
Mystik i'm an errand. Join Date: May 2002 Posts: 237 Rep Power: 0	imho, no project is dumb. =P But, from my experience, having the fan blow onto the heatsink gives better results. Also, if you just duct it normally, while still having it blow onto the heatsink, i think it would be better since it would always be blowing the ambient air outside, rather than using the air from inside your computer to cool the heatsink.. also, i'm assuming that you have at least another exhaust fan (not psu).. i think that way would work better. __________________ For as long as the sun shines, there will always be darkness. -- me.

Jan 2, 2003, 02:00 AM	Thread Starter #3
DriveEuro HardwareHeaven Extreme Member Join Date: Jul 2002 Location: Gurnee Illinois Posts: 4,677 Rep Power: 0	1 80mm 2500 intake front of case, 92mm 2500 rpm exhaust below cpu, 42cfm slot exhaust below vid card.... my 60mm 5000 rpm intake on the side of the case died last week. __________________ [color=orange]ASUS P4P800 Deluxe [color=black]-[/color] 2.4C --> 3300mhz [color=black]-[/color] Mushkin PC3200 at 220 5-2-2-2 (cpu limited) [color=black]-[/color] BBAti 9800Pro at 430/375 [/color] [color=black]3[/color][color=gray]D[/color]M[color=black]a[/color][color=gray]r[/color]k[color=yellow]01[/color] [color=black]3[/color][color=gray]D[/color]M[color=black]a[/color][color=gray]r[/color]k[color=yellow]03[/color] 16001200 12801024

Jan 2, 2003, 02:07 AM	#4
Mystik i'm an errand. Join Date: May 2002 Posts: 237 Rep Power: 0	If you want cooler temps, i think blowing onto the HSF with the duct would be better than blowing out.. since, as i said, it'll always be taking in cooler air from outside, rather than using the warmer air from inside your comp.. __________________ For as long as the sun shines, there will always be darkness. -- me.

Jan 2, 2003, 03:02 AM	Thread Starter #5
DriveEuro HardwareHeaven Extreme Member Join Date: Jul 2002 Location: Gurnee Illinois Posts: 4,677 Rep Power: 0	Eh... __________________ [color=orange]ASUS P4P800 Deluxe [color=black]-[/color] 2.4C --> 3300mhz [color=black]-[/color] Mushkin PC3200 at 220 5-2-2-2 (cpu limited) [color=black]-[/color] BBAti 9800Pro at 430/375 [/color] [color=black]3[/color][color=gray]D[/color]M[color=black]a[/color][color=gray]r[/color]k[color=yellow]01[/color] [color=black]3[/color][color=gray]D[/color]M[color=black]a[/color][color=gray]r[/color]k[color=yellow]03[/color] 16001200 12801024

Jan 2, 2003, 03:04 AM	#6
reno Painlord of Ichor Join Date: May 2002 Location: bloinkin! Posts: 1,610 Rep Power: 0	fdg Just leave it, ducting is overrated, forcing air over a HS cools the damn thing off much faster than sucking air over it. What feels better on a hot day? Blowing a giant air conditioner in your face, or sticking your face by the air conditioner's intake? Common sense.

Jan 2, 2003, 05:00 PM	#7
Matth Flash Banner Hater Join Date: Jun 2002 Location: UK Posts: 3,426 Rep Power: 93 System Specs	Turbulent air forced into a heatink by a close fan, has more effect than the same airflow generated by a fan on an 80-60mm funnel adapter, or the same volume pulled out by the fan. Blowing in, the flow tends to stick to the fins by bernoulli effect, while drawing out, the inward flow takes the easiest path. If the heatsink itself is "ducted", in the way that some very close pitch finned ones are, the drawing out MAY be as good as blowing in.

Jan 2, 2003, 07:29 PM	#8
Mystik i'm an errand. Join Date: May 2002 Posts: 237 Rep Power: 0	Alpha advertises their HSF's to work better when blowing away from the heatsink.. but when I tried this, my temps increased by +-3 celcius.. this was on an open case (side panel off).. I guess your milage may vary? __________________ For as long as the sun shines, there will always be darkness. -- me.