airflow suggestions

[hoax]

Once again trying to figure out the best way to setup case fans for a new build. Trying to come up with a setup to test positive pressure.

specs: 3770k, gtx680, NH-U12P SE2 push/pull, 3 internal drives + 1 ssd, sunbeam 6x30W fan controller

current plan:
http://i.imgur.com/Y3Ckt.png


questions:
- first time I have a case with a side intake. Wondering if with such a large side intake, would it be wiser to use less fans overall?

- should I add a fan to the floor of the case, near fan #5, and get rid of both 4 and 5 in the hdd cages?

- 2x top intakes or 1 top intake and 1 floor intake?

- this image is painfull to look at, here's what you should do: __________________________________________________

fan controller:
one channel for each pair: (2&3), (4&5), (6&7)
one channel for side intake
one channel for main exhaust
one free channel



a sample image in case anyone wants to share some l33t paint skills with suggestions for the 6 noctuas :P
http://i.imgur.com/leLHV.png


thanks in advance

[AMDforME]

Unfortunately there is no exact answer to what is the best means to obtain the best cooling for your PC short of carefully testing the various possibilities. The reasons for this are many not the least of which includes actual case design, hardware location within the case, fan speeds, airflow and static pressure, turbulence caused by the various components within the case, etc. Something as simple as changing the GPU card can have a significant impact on CPU cooling depending on the power draw and airflow over/around the GPU card and it's proximity to the CPU, what type of HSF you use and it's orientation.

That being said in general side case fans often work better to draw heat out instead of pushing ambient air in. Part of the reason for this is that you can stall the airflow thru the case by creating turbulence perpendicular to the natural flow of air thru the case. Only testing will tell you what works best for your particular case/hardware with your fans, thermal load, HSF, ambient room temp, etc.

Generally moving all the air from the front of the case to the rear is the most effective in cooling the hardware. Thare are rare exceptions but this would be the way I would approach your testing. I'd start without using the side fan, establish temps under stress testing, gaming or whatever would represent your worst case scenario, then try adding the side fan blowing in then blowing outward to see if the side fan helps or hurts cooling performance.

More fans is not always better either as they can create turbilence and or stagnent air pockets. They also tend to increase noise. Typically you want to use the least number of fans that deliver the best cooling without excessive or annoying noise. You may also find the top fans work better as exhaust fans instead of trying to blow anbient air in as they would also be forcing the hot air that rises in the case, back down into the case. This is why only actual testing can help you pinpoint what works best for your hardware.

As far as positive and negative pressure, the terms are often misused and misunderstood. Positive pressure does help keep dust out of the case if you use filters on the inlet fans. If not you'll get a lot of dust regardless. What really matters however is not positive pressure as much as good airflow. You can have positive or negative pressure and poor airflow and your components will still run hotter than with good airflow.

You can test for positive airflow by using a tiny piece of string or a strip of paper placed along side the various joints in the PC case. If the string/strip is drawn toward the case you have negative pressue and air being drawn in at the seams. If the string/strip pushes away you have positive pressure within the case.

[hoax]

Last time I created a similar thread the general advice was the same: try it! :slap:

still, every time I learn something new and its nice to hear different opinions from more experienced users.


I'd start without using the side fan, establish temps under stress testing, gaming or whatever would represent your worst case scenario, then try adding the side fan blowing in then blowing outward to see if the side fan helps or hurts cooling performance.

Hopefully I will be able to find the sweet spot with enough patience. First test only with 1, 6 and 7. Check temps. Enable 4 and 5 and check temps again. Then I will start testing effects of the side fan as you suggest, but honestly it never even occurred to me to test it as an exhaust.


You may also find the top fans work better as exhaust fans instead of trying to blow anbient air in as they would also be forcing the hot air that rises in the case, back down into the case.
this was linked in my older thread on this subject: http://www.silverstonetek.com/techtalk_cont.php?tid=wh_airflow&area=en

they claim top exhaust, when too close to another fan that is perpendicular, will cause both fans to fight for air, but I agree that each system will have too many variables to be sure.


You can test for positive airflow by using a tiny piece of string or a strip of paper placed along side the various joints in the PC case.
speaking of learning new tricks! :P

I knew about the effect near the case joints but didn't think of using a string to test, nice one.



thanks a lot for all the feedback, I really appreciate it! :up:

[Dk_vr]

If you ask me, the best option indeed is try it.
As personal advice I can tell you, stick to same fans not different as much as possible.

[apexracing]

You really have to experiment with fan placement, every system is a bit different. Your case has lots of fan spots, so there are many configuration options.

[AMDforME]

Hoax-

Glad to help.

With all the possible combinations, you will be busy for months learning... and that's a good thing! :D

[CrazyNutz]

general rule of thumb on fan direction is:

front & bottom = blow cool air into case

top & back = exhaust warm air out of case

[chinaguy]

I have a very simular setup for my coolermaster 690. All the fans blow in apart from the ones on the top of the case. I use a Lian Li Fan Control to reduce the speed/noise of the fans when required, in the summer with no AC on the fans run full on, now in winter I can turn them down.

Must be running 7 fans in the case in the summer time, no in winter only the fan blowing over the HDs is on full and the back MoBo 70mm fan/top fan is under the control on the MoBo incase it starts to get warm.

[hoax]

Fans are currently stuck at customs so I can't begin testing yet. I will be sure to update the post for future reference after testing out a few options.

Huge thanks for all the feedback guys!!