Airflow direction

lordroba · Post by **lordroba** » Sun Jul 10, 2005 4:58 pm

There are currently 3 fans working in my computer: the fan from the power supply which is blowing air out, the CPU fan, which is sucking air in from the inside of the computer and blowing it at the CPU, and then there is my new fan that is installed at the back of my case. This one is at a 90 degree angle to my CPU fan. My question is, should I have this third fan blow air into to the computer or blow air out? Which would be better and why? Thanks

Btw, here is a lovely diagram I made in Paint to get a better visual idea of what is going on. (The new fan is the blue one)

dokool · Post by **dokool** » Sun Jul 10, 2005 5:49 pm

It should be blowing in:

First fan: brings fresh (cold) air inside
Second fan: blows air already in the case against the processor
Third fan: brings air in case (hot) out

At least I think that's how it should go

TaranT · Post by **TaranT** » Sun Jul 10, 2005 6:14 pm

PC airflow and heat - a cooling guide

lordroba · Post by **lordroba** » Sun Jul 10, 2005 6:26 pm

hmm...

I tried the recommended configuration from the site: putting a fan in back as a rear exhaust. I'm getting a motherboard temperature of 35*C, CPU temp of 60*C and HD temp of 35*C. Is this a decent temerature reading or should I try to lower it even more?

TaranT · Post by **TaranT** » Sun Jul 10, 2005 9:50 pm

The board and HD temp's seem to be ok, but the CPU temp...may be high if you're using a P4, or may be normal if you're using an Athlon. You might try re-seating the heat sink just to be sure. Or maybe try a larger heat sink/CPU fan.

More about CPU temps here.

The same site has some info about case cooling.

jbone · Post by **jbone** » Sun Jul 10, 2005 10:08 pm

CPU fans never blow air at a CPU; blowing hot air at a CPU would be counterproductive.

CPU fans draw hot air away from a CPU.

TaranT · Post by **TaranT** » Mon Jul 11, 2005 2:35 am

That seems to make sense, but in my experience the fans are always blowing toward the radiating fins, however they might be arranged.

These are some links to Thermaltake coolers. There are pictures showing the airflow.

http://www.thermaltake.com/coolers/venus/rs/a1744.htm
http://www.thermaltake.com/coolers/venus/rs/a1838.htm

Also, this from CoolerMaster:
http://www.coolermaster.com/index.php?L ... &serial=38

lordroba · Post by **lordroba** » Mon Jul 11, 2005 5:00 pm

kk, Thanks for all your help everyone. I'll make sure to consider this when I'm installing my third fan (maybe next month)