Should a Side Fan Blow in or Blow Out?

[LouTheBlueGuru]

I did some research on this topic and most agree it should blow into the case (a search on this site and forum)! This seems wrong to me. What is your opinion? My machine has a front fan that sucks air in and a rear fan that blows air out. I would think that a side fan should pull the hot air off the cpu heat sink and blow it out.

DFI NF570-M2/G
AMD 64 X2 5600+ @ (14x200) with Cooler Master Hyper TX
4x1024 Corsair XMS PC2 6400 @ 4-4-4-12(2.1v), 2T
Corsair 520 PS
XFX 8600 GT Video
WD3200AAKS 320 Gig
Emu 0404
Abit AirPace wireless Nic
OS - none execept DOS 6.2 on occasion

[Stevea]

You have a front fan blowing in, and a rear fan, and the PSU sucking air out.

1 extra fan blowing air in, evens the flow volume out.

[_dangtx_]

in from front,side,bottom. out from top,rear

[Mjölnir]

The area around the CPU fan is generally surrounded by hot air. The side fan draws cool air from outside of the case directly to the CPU fan, which is why many of them have the funnel. The outside air should be cooler than the air inside the case.

[John C]

In addition, 99% of all CPU fans blow down onto the CPU, so if a side fan is directly opposite the CPU fan, and blowing in opposite direction, they will fight each other and reduce the effectiveness of both. But as always, try it both ways and see what your case temps are. Sometimes things just work against logic!

[_dangtx_]

i also tend to leave the backplate out of the equation soemtimes. bit more breathing for that cramped area

[LouTheBlueGuru]

Well, I appreciate all of the feedback. Note the Coolermaster heat sink fan blows air form the front, through the HS, to the back of the case in my system, not from the top down. Based on the heat funnel idea with the funnel channeling air from the HS to the outside of the case, it seemed to me the side fan should blow air from over the HS to the outside of the case. My case did have a funnel but the HS was so tall I had to remove it.

OTOH, I can appreciate the point of view that says the side fan should blow cooler air from outside the case onto the HS. Given fan speeds, this would build up pressure inside the case and cause greater airflow out the back of the case.

In conclusion, I don't think anyone has a definitive answer, so as was suggested I need to try both approaches. If anyone is interested, I can report back.

Note: I'm not sure how the PS fan factors into this equation.

[Stevea]

Actually you would want positive pressure inside the case, that way if the PSU fan increases speed it will not be starving for cool air.

Also helps keep the dust bunnies out.

And yes report back with you findings, it will help some else down the road with the same question.

[DJFrostbyte]

I have an 80mm fan on the side of my case and have tried it both ways. I noticed really no obvious temperature changes with it blowing in vs. out, BUT when it was blowing out, i noticed my HS fan making more noise, i figure from the struggle between the fans. So I turned it in as an intake fan and added a second 80mm fan blowing out the back. Just thought I would add my .02 from experience. Of course all cases and fans are different and my side fan is directly across from my HS and my HS fan blows down onto the HS, not across it like yours does. So definitely try it both ways and report back, i'm interested to see what results you get.

Rob

[Mjölnir]

Air pressure for me is a moot point. You're always gonna get dust bunnies in a dusty or carpetted area and air will still find a way out. Fans simple accelerate the process. In any case, more airflow out of the back of the case is a good thing because the fans/vents there are high up and close to the main hot spot (near the CPU, VGA card and chipset).

[Brandito]

good air flow design is the more elegant method, bring it in low from the front and exhuast it high out the back, but keeping it moving back to front with as little resistance as possible is what i find works best.

the brute force approach of putting tons of fans blowing in and out from all points is indeed effective, but not very efficient i should think. it creates turbulance which may negate the effects of other fans in the system.

until someone does some indepth highly scientific study it's like the world will never truely know.

i also like positive pressure.

[MixedNuts]

I did some research on this topic and most agree it should blow into the case (a search on this site and forum)! This seems wrong to me. What is your opinion? My machine has a front fan that sucks air in and a rear fan that blows air out. I would think that a side fan should pull the hot air off the cpu heat sink and blow it out.

DFI NF570-M2/G
AMD 64 X2 5600+ @ (14x200) with Cooler Master Hyper TX
4x1024 Corsair XMS PC2 6400 @ 4-4-4-12(2.1v), 2T
Corsair 520 PS
XFX 8600 GT Video
WD3200AAKS 320 Gig
Emu 0404
Abit AirPace wireless Nic
OS - none execept DOS 6.2 on occasion

My temps are a little on the Hot side. I'm running about 55 c CPU and 35 c system temp.
If I remove the side cover I can see the temp drop to 25 c System and 45 c CPU.
I'm going to add a fan to the side cover right over the CPU fan. Hopefully this will keep the temps low with the side cover in place.
I'm not sure if the fan size will be 80mm or 92mm. I'll let ya know.

[richardd43]

Here is how Silverstone laid out the cooling for the TJ07:

Cooling System
Top: 2 x 120mm exhaust fan, 1200rpm, 21dBA
Rear: 2 x 92mm intake fans, 2100rpm, 23dBA
Bottom: 2 x 120mm intake fan, 1200rpm, 21dBA

Because I did not use the HDD case in the bottom of the case, I disconnected the lower fans and installed a 120mm side fan to assist the CPU cooling.

[Brandito]

Because I did not use the HDD case in the bottom of the case, I disconnected the lower fans and installed a 120mm side fan to assist the CPU cooling.

why? the front fans would likely aid cooling better ythan the one on the side. better more efficient airflow.

[richardd43]

The TJ07 does not have a front fan. The lower fans are part of the 2 HDD cages and suck air in one side and blow it out on the other. As these cages are mounted on the very bottom of the chassis I saw no need for them to be on. They would contribute little to the overall case temperature.

In fact, I removed one of the cages to better accommodate the wiring from the 2 PSUs that are installed (also in the bottom of the case).