Is Physics Useless?

[syllepsis]

I think I want my money back for my Engineering Physics BS.

Here is my (non) problem.

I have a Noblesse case, athlon 1800+, Thermaltake Volcano 7, and two quiet 80mm case fans blowing OUTWARDS right by the CPU under the PSU.

I have NO intake fans. My MB Temp reading is 25 deg C. (about 3-5 degrees above ambient)

My CPU reading is 48 deg C under load, which I plan on working on.

WHat drives me nuts is that when I had front blowers and rear intakes, and positive air pressure in the case, I got MB temps of 37 deg C.

Now that I am doing everything (apparently not) wrong, the airflow in my case seems to be spectacular.

What gives?

-Syllepsis

 

[sodcha0s]

When there is positive pressure in the case, the air inside is not changed over as often and continues to tumble around, all the while absorbing more and more heat. This naturally raises the temperature inside. With the negative pressure you have now, you are constantly bringing in fresh cooler air, it absorbs some of the heat, and it is exhausted before it is able to warm the inside temp. The problem with this setup is you'll tend to pull dust in through every crack and crevice, including CD Rom and floppy drives.

 

[syllepsis]

Thanks Sod,

Your explanation makes alot more sense than what I have heard so far.
You know of any place where air pressure and cooling physics are well explained on the net? I would like to get a real understanding of this, because it is fun to play with.

I will see if I can even out the pressure.

-Syllepsis

 

[Supradude]

If you wanna go hardcore... look up into heat and mass transfer (fin analysis) and basic fluid flow dynamics... with some basic equations you can model your case and system as a simple system and you can calculate the effectivesness of your case and fans... hehe

 

[Lord Evermore]

There's a reason every airflow description doesn't say to set all the fans to blow IN, but rather to create an actual stream of air.

 

[sodcha0s]

No problem syllepsis,

Don't know of any sites offhand, I'm sure you'll come up with something if you take Supradude's advice. I have a degree in HVAC, and naturally that deals with a lot of airflow properties, static pressure and some basic laws of thermaldynamics. Learning just the basic laws of thermaldynamics will give you a much greater understanding of heat transfer and properties, there seems to be a lot of confusion on this topic in this forum by some of the statements I've seen. Good luck, and let us know if you find any good sites on these topics...