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Summer is around the corner, time to rethink my airflow. - Page 2

post #11 of 59
Quote:
Originally Posted by amurph0;13058474 
Also hot air doesn't rise when it's being pushed by fans. It'll only rise when it's in one position for too long.

You don't see the hot air coming out of a hair dryer going straight up as soon as it comes out of the nozzle do you? No. It goes in a straight line, and only begins to rise when it slows down.

Only static hot air rises, not moving hot air.

3 factors of consideration for the OP:-
1) Air velocity
Hot air coming out of a hair dryer has 'high' velocity.
However, hot air exhausted from a graphics card and a PSU has very small velocity, particularly when compared to a typical computer case fan of 120mm size. Just put your hand and feel it (or rather, not feel it).

2) Proximity of a strong Intake fan
Actually, the 'rise' is mainly due to the suction created by the fast spinning 120mm rear case fan which just sits 2-4'' above. At such a short distance, it is unavoidable to intake the majority of hot exhausted air.

3) Insufficient space
If OP's case is located with little space behind and/or poor ventilation, it takes little time for the hot exhausted air (from video card and PSU) to fill up that region because natural convection is so little.

Perhaps the best way is to actually try it. With the rear case 120mm fan as intake and as exhaust and see its impact on temperature (especially CPU's).
post #12 of 59
Quote:
Originally Posted by windfire;13058749 
3 factors of consideration for the OP:-
1) Air velocity
Hot air coming out of a hair dryer has 'high' velocity.
However, hot air exhausted from a graphics card and a PSU has very small velocity, particularly when compared to a typical computer case fan of 120mm size. Just put your hand and feel it (or rather, not feel it).

The hair dryer was an example of how hot air doesn't always rise and wasn't a comparison to case fans.
Quote:
Originally Posted by windfire;13058749 
2) Proximity of a strong Intake fan
Actually, the 'rise' is mainly due to the suction created by the fast spinning 120mm rear case fan which just sits 2-4'' above. At such a short distance, it is unavoidable to intake the majority of hot exhausted air.

That isn't hot air rising, that is just air being sucked in by another fan and it would happen regardless of the temperature of the air.
Quote:
Originally Posted by windfire;13058749 
Perhaps the best way is to actually try it. With the rear case 120mm fan as intake and as exhaust and see its impact on temperature (especially CPU's).

Agreed. The only way to find out what works for you is to try different setups yourself and see what works best.
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post #13 of 59
Just remember, heat rises. Point those CPU fans up and exhaust all top air up and out. Flow that cool air from the front to the back. Intake from the side.
    
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post #14 of 59
Thread Starter 
Quote:
Originally Posted by UrbanSmooth;13058833 
Just remember, heat rises. Point those CPU fans up and exhaust all top air up and out. Flow that cool air from the front to the back. Intake from the side.

My heat sink can only be placed horizontal. I'm about to try the suggested set-up and I'll get back with results. Hopefully with one less 140mm fan spinning I'll get a little audible difference.
post #15 of 59
Quote:
Originally Posted by amurph0;13058474 
You should have a look at this guide by Silverstone:
http://www.silverstonetek.com/tech/wh_airflow.php?area=usa

Point number 6 in the guide is something I've found interesting. And it contradicts what most people would say about airflow at the back/top of a case.

Also hot air doesn't rise when it's being pushed by fans. It'll only rise when it's in one position for too long.

You don't see the hot air coming out of a hair dryer going straight up as soon as it comes out of the nozzle do you? No. It goes in a straight line, and only begins to rise when it slows down.

Only static hot air rises, not moving hot air.

Are you seriously comparing case fans to a HIGH VELOCITY hair dryer fan? You still must be an amateur (No offence). But seriously, case fans are weaker than even normal fans that you have in your room when you don't have A/C. Please, know what you are talking about before you speak. I do not respect ignorance.
post #16 of 59
OP - I'd get rid of the side panel fan, and close up that hole. I'd make sure the inlet fan by your drives is not obstructed so you still get nice airflow in to the GPU area, and keep to a nice front to back design. I'd probably put a nice filter in where the intake fan is, and move the fan to the other side of the drive bay so there is some insulation to prevent the sound from the fan bleeding straight out of the front of the case.

I'd also be tempted to seal up both the top fan slots, use an air intake from your unused optical drive bays and a single exhaust fan on the back of your case. I'd also remove the 'pull' fan from your heatsink and run just the read case fan and the 'push' fan. Again I would build a duct from the front of the optical bay so you can move the fan away from the front of the case and isolate it with filter medium so the noise doesn't come out but the air can come in.

More fans often gives worse cooling and more noise than fewer fans does. You need to think about how the air moves through the case (and how the noise gets to your ears), not just about how to fill all the fan mounts in your case.
post #17 of 59
Maybe something like:
IMG_4681_2.jpg
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post #18 of 59
Some thoughts...
(1) heat rising is also dependent on the relative temperature/density of the surrounding air. It's not heat per se that rises, but warmer/less-dense air being "squeezed" upward by surrounding cold/dense air. In the absence of air, heat radiates omni-directionally.
(2) With the above in mind, determining whether heat rises inside a case depends on the air volume inside the case and the ambient temperature inside the case. Heat is more likely to rise in a spacious case with good cool air intake. Your setup should vary accordingly.
(3) Finally, regarding "plagiarism" on this site...we're all basically having a conversation here. We may pat each other on the back when the situation merits it (rep) but it's not like school where you are stealing someone else's credit. Taking yourself too seriously is a guarantee that neither you nor the people you're chatting with will enjoy being here.

Just sayin' biggrin.gif
post #19 of 59
Thread Starter 
Thanks everybody. I just got back from moving some fans around to what paratrooper and windfire suggested, and I got quite a difference in temps. 3-4 Celsius idle and at least 5 under load. Getting rid of one of the 140 mm didn't give me a change in noticeable noise, but those are hardly the culprit when it comes to noise polluters. As for adding a 120 mm in the bay area, I might do that if I get bored and have an extra fan at one point and want to try for over 4GHz. Right now I'm pretty satisfied with my temps and overclock, but I'm still open to suggestions as I love information.

A couple weird things. HW monitor isn't seeing a "FANIN1" like it used to. It only sees a "FANIN0" and one of my CPU fans is now under the PWM section. All the fans are the same, and plugged into the same spot as they were before. So that's weird. Also, the now "pull" fan doesn't spin immediately at start up anymore. It takes a few minutes for it to kick on. Again, same fan, same spot as before. I have checked that they are fully pushed in and nothing is obstructing it. Any clue as to what might have happened?
post #20 of 59
just get an air conditioner and route the air via tube to the front intake lachen.gif
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