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CPU Fan Direction

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Last response: in Components
September 3, 2009 7:27:17 AM

EDIT: http://www.antec.com/demo/p182/p182_flash.html This video shows the air flow in the case.



Zalman CPU Fan/HS

OK, conventionaly the CPU fan blows towards the rear and rear case exhaust. I can have my fan blow in either the up or rear (left) direction. It would seem that blowing up would directly suck the air in from the front intake fans, creating a stronger flow of fresh air through the system.

What do you all think, up or left?

More about : cpu fan direction

September 3, 2009 8:21:24 AM

Ha!....is that an antec p183? I just built a system using one of those! I used the Megahelems as the cpu cooler. Since my cabling blocked most of my airflow from the HDD bays on the top, and the bottom did little to bring air into the upper case, I reversed those fans to exhaust the warm HDD air out the front. Since the cpu lines up perfectly with the top front external bays, I let the two open ones act as the cool air intakes and lined up the two cpu fans to blow the warm air out the back. The top fan helps draw the warm air from the video card up into the strong air stream from front to back, also helps with any residual heat that excapes the air stream. I was using a passively cooled video card in hopes for a silent build, and even though I used silent fans througout I still have a decent amount of noise created by the "woosh" of the air moving through the case. Cpu is overclocked to 4.0, and top temps on the cores during a long prime 95 torture test reached mid 70s...in actual use its never topped the mid 60s.
a c 173 à CPUs
a c 144 ) Power supply
September 3, 2009 8:43:35 AM

I have Antec 900 cases. I orient the HSF vertically to take advantage of the large fan on top. I figure that warm air wants to rise. Why fight physics.

I thought about doing some tests to see which way really does work better, but it was such a PITA that I decided not to.
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September 3, 2009 9:46:26 AM

I'de like to mount a fan in the top front bay but I dont think the case is made for that (Antec p182). Also, turns out that when I plug my video card in its a real tight fit (cable pressed against fan housing) with the fan in the middle, so I may exclude the middle fan and just let the one in front of it be the intake. With this is mind I'll try to move that middle fan up into the front bays....tomorrow though, after some sleep.
a b à CPUs
a b ) Power supply
September 3, 2009 12:28:01 PM

Depends on whether you think your VRMs (and chipset if connected) needs the air blowing over it as a CPU cooler can help there whereas the exhaust fan moves little air past VRM 'sinks.
a c 246 ) Power supply
a b à CPUs
September 3, 2009 12:34:06 PM

+1 what mi1ez said.

Which motherboard do you you have?
September 3, 2009 12:37:13 PM

you won't need a fan in the top bays if your cpu cooler fan is strong enough....you can feel the air moving through there even without the fan...because of the way the case is segmented the cpu fan is pretty close to the back of those bays, so it creates a natural wind tunnel.
September 3, 2009 5:13:37 PM

My MB is a HGigabyte ga-ma790x-ud4p

http://www.gigabyte.com.tw/Products/Motherboard/Product...

When the CPU Fan is positioned to blow vertically, the heatsink is rather close to the memory slots (all full - the hs is close to the plastic heat disaptor things on the RAM http://www.newegg.com/Product/Product.aspx?Item=N82E168... ). I dont think thats a huge problem, but it is a consideration.

I mentioned above, the vide card http://www.newegg.com/Product/Product.aspx?Item=N82E168... is really pushing it for length after I plug in the power, so the middle fan closest to it might be out. Side question: why does this card use two power cables?

Another side question: I would like to get a couple cable extenders so I can route my power cables behind the MB tray. Where do you guys recomend I look for quality extenders?
a c 246 ) Power supply
a b à CPUs
September 3, 2009 5:53:58 PM

Orient the cpu fan so that it blows from front to rear. You have a large blue colored heatsink between the cpu socket and the rear parts. You have memory banks on the opposite side of the cpu socket. Pretty simple.

It is aboslutely normal for large cpu heatsinks to be near or over the memory modules. Sometimes memory modules with extra tall heatspreaders will prevent the use of a large cpu heatsink. That's why I don't bother with them. I let the cpu heatsink fan pull air of the memory moduels.

A variety of extension cables are available from many online vendors, including newegg.com

a b à CPUs
a b ) Power supply
September 3, 2009 5:57:38 PM

I have the same case, and here's what I've done:

- removed the fan from the lower chamber and blocked off the vents around the power supply opening. I'm using an Enermax 82+ power supply and it's fan is plenty good enough to pull air through the lower chamber and keep the hard drives cool.

- one Antec 3-speed fan set to "low" just behind the upper air filter. (There's no point having two fans as you have in your diagram, they aren't going to move any more air.)

- rear and top Antec 3-speed fans set to "low" as you have in your diagram.

I also use a Thermalright HR-01 heatsink with a Scythe Kama fan - the fan is mounted on the side of the heatsink that faces the front of the case and blows toward the rear opening. The system has a passively cooled ASUS EAH-4350 graphics card.

With all of the fans on "low" there is hardly any noise from the system. The heat spreader temps on my Core i7 idle at around 40C and peak at about 65C after several hours of Prime95. The video card runs at less than 55C and the hard drives peak at about 39C. Interestingly, the hard drives get cooler under a heavy load because the extra power draw causes the PSU fan to run faster, thus drawing more air through the lower chamber.
September 3, 2009 6:14:19 PM

Typically, it's best to have the fan blow from front to rear. That way it sucks in cool air from the front of the case. When mounted vertically, it sucks in hot air coming off the back of the video card.
September 3, 2009 11:22:08 PM

Thanks guys, you have helped clear up some confusion and misconceptions.