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A small correction regarding the laws of thermodynamics and convection. - Page 2

post #11 of 108
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Quote:
Originally Posted by psyclum View Post

the importance and relevance of convection cooling is often OUTSIDE the box.... to discount convection entirely is uneducated at best... yes inside a box, any kind of fan would overpower the action of convection, however, this does not negate for physics behind heat rising to the top. with a top side intake, you are often recirculating hot exhaust from PSU/GPU/CPU right back into the case and causing further inefficiency in your overall cooling solution. this problem is especially acute if the computer is in a semi enclosed area such as under a desk where hot exhaust is trapped by the desktop and then sucked back into the case from the top side intake.
recirculation of hot exhaust (thermal short circuit) creates inefficiency and as a result higher decibel levels then necessary to achieve the same goal. overall cooling performance may not be very noticeable however the real discussion in PC cooling really lies in long term decibel level. anyone can cool anything if they used enough 5000rpm delta fans, however, to keep it under acceptable decibel levels, one must search for efficiency and this is where consideration in convection comes into play
a bottom intake and top exhaust ensures maximum separation between cool intake air and hot exhaust air because OUTSIDE the box, hot air WILL rise and convection DOES work...

I know the thread is very old but I just wanted to answer your comment. The air outside the case doesn't matter either for these reasons:

1) If you have your case in an open space, the amount of air is so large that the probability that exactly the same air is pulled back into the case is minimal at best. Anyway, because of the laws of thermodynamics, the heat would have a tendency to dissipate itself into the rest of the air to maintain a certain balance.

2) If your have your case in a small space like the little compartments that they put in many desks, air will be recycled anyway and you should just get it out of there if you want better temps.
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post #12 of 108
Most cases will have one or more airflow obstructions near them... chair, ball, desk top, human leg, etc. The resulting contamination of cool intake air by hot exhaust air will be the result of how these obstructions interact in airflow.
post #13 of 108
I dislike the idea of having the top of my PC for intake for one reason and one reason only...

Dust....
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post #14 of 108
Thread Starter 
Quote:
Originally Posted by Ganf View Post

I dislike the idea of having the top of my PC for intake for one reason and one reason only...
Dust....

Of course that's something you have to take into account but some cases have top dust filters like the HAF X if I'm not mistaken but cooling wise, a top intake is often better than a top exhaust especially for watercooling.
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post #15 of 108
Quote:
Originally Posted by Snowmen View Post

Of course that's something you have to take into account but some cases have top dust filters like the HAF X if I'm not mistaken but cooling wise, a top intake is often better than a top exhaust especially for watercooling.

No filter is going to catch it all though, unless you let it get so clogged up with pet hair that it can't be seen through. thumb.gif and it's the fine dust that kills components. The chunky stuff is ugly sure, but it's not going to get into your ram slots, the bearings of your fans, or the back side of the board. It's the talcum powder fine dust that will end up costing you money, and the only way to keep that out is by setting your intake low and your exhaust on top, with positive pressure. Or don't get a case with an open top.
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post #16 of 108
At the moment, i only have one active fan (NOCTUA 120mm @ 1500rpm) on my corsair 300r and that is on my antec 620 radiator as a push exhaust on the top of the case.. I did some tests and see no big difference on performance with more fans on the case.... But i guess people here thinks more fans are better... So be it.. XD

The rest of the cooling is been doing passively and using the case aerodynamics to my advantage..
The only fan i hear now is the gpu fan and i would kill that one soon too...

http://www.overclock.net/t/1267656/aircooling-test-for-gurus-xd/10

I dont like theorys i like actual facts, hence my tests and their results with graphs..

What ifs dont count..... Test your system.. More fans dont equal better performance...
Edited by zGunBLADEz - 6/10/12 at 4:08pm
post #17 of 108
Thread Starter 
Quote:
Originally Posted by zGunBLADEz View Post

At the moment, i only have one active fan (NOCTUA 120mm @ 1500rpm) on my corsair 300r and that is on my antec 620 radiator as a push exhaust on the top of the case.. I did some tests and see no big difference on performance with more fans on the case.... But i guess people here thinks more fans are better... So.. XD
The rest of the cooling is been doing passively and using the case aerodynamics in my advantage
http://www.overclock.net/t/1267656/aircooling-test-for-gurus-xd/10
I dont like theorys i like actual facts, hence my tests and their results with graphs..
What ifs dont count..... Test your system.. More fans dont equal better performance...

That's probably because the Corsair 300R is pretty much made out of mesh. Your two main heat producers, the CPU and the GPU, are properly cooled because your 620 has a fan on it and the GPU is surrounded by mesh so it's almost as if it was running in the open (like a test bench).

The number of fan matters but only if you place them properly. Also, if you have that 120mm fan exhausting, the gpu also exhausting with a blower style cooler and your PSU facing up, these are all taking air out of the case. Now, the case can't simply be "filled" with void so cool air will eventually get in.
Edited by Snowmen - 6/10/12 at 4:13pm
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post #18 of 108
Like i said everybody need to do their own tests to find out.. if you think more fans are better just to have a ease of mind fine with me..
I even block my side panel mesh with cardboard to do this tests.. My findings? Only 1 fan needed...
My case only open is the top which is good for me it helps me alot XD...

Less fans, Less dust on my components..
post #19 of 108
Sorry this is wrong. You should not have you radiator doing air intake. I have done extensive testing with several cases and radiator combinations and always the exhaust radiator improves thermal performance. While intake radiator leads to un-wanted side effect as higher motherboard temps, hdd temps, and gpu temps.
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post #20 of 108
Quote:
Originally Posted by Acefire View Post

Sorry this is wrong. You should not have you radiator doing air intake. I have done extensive testing with several cases and radiator combinations and always the exhaust radiator improves thermal performance. While intake radiator leads to un-wanted side effect as higher motherboard temps, hdd temps, and gpu temps.

Dude you realize im maxing out on IntelBurnTest (IBT) @ 70/72c (14800mb ram loaded on a single test) for maximum constant heat to find out my cap, Thats almost 8minutes of constant abusing NON STOP with a non-realistic load... You cant find nothing out there that abuse your cpu like IBT/LINPACK 64, i guaranteed you that..

I dont really care in the couple of extra -c im going to gain putting my fan on the radiator as a intake... It dont benefit my overall system at all, i think it would get worst as it pushing that heat inside.....

Theres no way, no program out there load my cpu as much as IBT not even prime with @ 12hr test would do that...
Guess what, i only need 8minutes of IBT to do something prime95 cant do witth 12hrs....
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