Intake and Exhaust Fans

[Soccer55]

I have a PAL35T w/ Delta 38 cfm fan. It is my understanding that in order to have good airflow, I should have the intake and exhaust fans moving roughly the same amount of air as the fan on the Alpha. I was wondering how true this is. I have 2 30 cfm 80mm quiet Sunons: one for intake and one for exhaust. Thanks in advance.

-Tom

 

[SilverBack]

Well, look at it this way....
The intake fan will bring in air at a certain rate, the exhaust fan will dispel it.
If you take two different CFM's the fans will normalize. For example if the intake is 20 cfm and the exhaust is 30 CFM they will average as the fans will always try to equalize the pressure in the case.
What this means in relationship to the fan on the HSF..... Doesn't mean anything. The HSF simply pushes air over the heatsink at X feet per minute. This won't impair the pressure inside the case at all.

 

[Brig]

".....in order to have good airflow, I should have the intake and exhaust fans moving roughly the same amount of air as the fan on the Alpha."


IMHO, that statement is not true at all. Reason being that the cpu fan cools the cpu by using existing case air, which is itself kept cool by the intake/exhaust fans. When hot air is pulled away from the cpu, it is only expelled into the case, where the system cooling fans take over to remove it. Two seperate operations.

The balance in moving air should be between system cooling intake and exhaust, with maybe a slightly higher intake. I think the system cooling airflow should be much higher than that of the cpu cooling.

 

[Runequest2]

maybe i am being dense but shouldn't adding a fan cool down a system? I just added a sparkle 34 cfm fan for additional exhaust. i had the power supply fan as exhaust already, a front fan for intake and a slot fan that has a two fans one intake and one exhaust. the new fan is right near the cpu. the motherboard readings went down some (they were 28- 29 C now 26- 27 C)but the cpu seems to be a degree higher 45 C- 46 C now 46 C- 47 C. this is with just web surfing like now . should i try switching it around and have it become an intake fan? readings are from the asus probe v 2.11.

superpower case 202 xp with 300 watt sparkle power supply
http://www.spower.com/202.htm
p3v4x
p3 800E
224 MB pc100
20 GB maxtor 7200 rpm HD
10 GB IBM 5400 rpm HD
toshiba 6x DVD rom drive
hp 9100i cdrw 8x4x32
V3 3000 AGP
sb live value
I have not over clocked anything... yet

 

[Jubjub]

Hi Runequest,

You might want to look for "short circuits" in your air flow created by the placement of your fans. For instance, when you mentioned the slot unit (one fan intaking, one fan exhausting), it raises the possibility that the exaust fan of the pair is just sucking out the cool air from the intaker before it can have a meaningful impact on system components.

Your new fan might actually be exhausting cool air away from your CPU before the air has a chance to cool it. Just a thought...