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Which way to use case fans

Last response: in Overclocking
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July 6, 2011 12:05:13 AM

My new case as 2 120mm case fans on the side panels, a 120mm front fan and a 120mm exhaust fan. I'm running a EVGA GTX 460 SE (hoping to overclock) and a AMD Phenom X4 9650 OC'ed to 2.6GHz. I was wondering if I should have the side panel case fans blowing cool air onto my case/GTX 460/CPU or should I have them exhausting hot air out of the case with the front fan blowing cool air into the case? Or if anyone could tell me by looking at pictures of the case how I should exactly orient my fans to keep my components the coolest, that would be great.

the case:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

specs:
AMD Phenom X4 9650 - 2.6GHz
Arctic Cooling Alpine 64 Pro Rev. 2 CPU Cooler
7GB DDR2 RAM
Asus M4A785-M Motherboard
EVGA GTX 460 SE 1GB
Corsair CX500 PSU
Seagate Barracuda 1TB HDD

Please reply, Thanks.

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a b K Overclocking
July 6, 2011 1:00:04 AM

It is important to understand that the effectiveness of cooling is also dependant on the ambient temperature of the room the computer is in. There are; however, some people who strongly uphold that positive air pressure keeps the system cooler, whereas the other who find that negative air pressure does it better. Of course, you have to also consider neutral.

The logic behind positive and negative pressure is based on the airflow cubic foot/feet per minute (CFM). With more intake fans (positive) you'll theoretically have more cool air being sucked in; while having more exhaust fans will theoretically pull more warm/hot air out. Of course, neutral is neutral; same CFM coming in as going out.

The OEM (or OEM-style) heatsinks are designed with top mounted fans that pull the hot air away from the heatsink, thus logically, it would stand to reason that putting the side panel fan in the exhaust orientation is ideal, if using a top-mounted HSF. But if the aftermarket cooler has a side-mounted fan (which most do), then the side panel exhaust fans may be less than ideal. That said, there are pros and cons to both schools of opinion:

Positive CFM:
More air coming, but also more dust. Still a question remains, is the amount of cool air coming in enough to cool down the system?

Negative CFM:
More air going out, but the lack of cool CFM could cause your devices to heat up too quickly. So the question is: Is the negative CFM high enough to keep the devices cooled?

I would do some testing to see what works best for you. First, download and install Prime95 and Speedfan or CPUIDs HW Monitor.

Test 1: Build your system with the side panel fans blowing air out. Now run P95 and Speedfan or HW Monitor. Record the CPU and GPU temps after running the system for an hour.

Test 2: Build your system with the side fans sucking air in, and then run the above mentioned software. Record temps and compare with results of test 1.

Note: To get accurate results of both tests, the system should be powered on from a cold boot.
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July 6, 2011 2:51:53 AM

Best answer selected by alexohlol.
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July 6, 2011 2:52:38 AM

Thank you very much for the info. I will download those software and see which one suits my system better. :) 
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July 6, 2011 3:05:02 AM

actually, what would happen if the top side panel fan was blowing air into the case and the bottom side panel fan was blowing air out ? would it just cancel each other out ? the side panel fans are next to each other by the way.
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