The ultimate airflow thread :D

[RedFury]

Alright, I've read a few comments here on case airflow. We need some definitive guesses on what constitutes proper airflow through a case.

Besides the obvious need to clean up the clutter, say we are dealing with different case designs and need to figure out the best scenarios, because I'm having a helluva time trying to figure out what is going to give me the best results with my final configuration....

Here's my deal. I've got 5 80mm fans on the front and back combined, and one 120mm blow hole on top ( it's huge! )

Looking at it running with no Motherboard, it almost seems as if I have some dead zones and swirling of dust that I hadn't gotten cleaned out yet. I cut up a dryer sheet and hung it in the middle of the case and it just flopped around a bit, but basically hung in one spot. This configuration is 2 80mm in, 2 80mm out + 120mm out ( running on an exterior powersupply, the PS fan wasn't running ). When it is all built, I'm looking at 3 80mm in back blowing out, 2 80mm in front sucking in and a 120mm blow hole.

The math, for one doesn't seem to add up. I'm considering running it in the configuration shown in the picture I attatched.

Since I have no side fan, I'll have 2 80mm sucking in the front, 2 80mm sucking in the back ( plus adding fresh air across the Heatsink ) and the PS 80mm + 120mm blow hole pulling all the hot air right out the top and top back.

Suggestions, Comments?

[Telexen]

I don't like drawing air in from the back. It may work very well for some people, but I really feel that if your case is even near a wall - then it's pulling in warm air from the PSU.

With Chieftec/Antec cases, or any case where there are two fans in the back - I don't think a top fan is necessary. Especially if you have a dual fan PSU where the bottom fan is pulling air into the PSU.

[vass0922]

ya.. those back fans should be blowing out

[CERuppel]

Just two comments:

Aren't those Antec cases sweet?

And yes, I have been wondering about those same airflow concepts (not for about four monthes, I admit, but I did have these same thoughts).

My concept solution (not yet implemented) was similar to yours. The difference was that I wanted to include a video card exhaust fan. Saw one that fits into a card slot and exhausts the area directly in front of (or under, if you prefer) the video card heat sink directly out the back of the case. I also have been of the opinion that a top blow hole is the way to go for heat removal.

This thread will be very interesting to read later, after the case modding masters get a hold of this line of thought. Thanx

[RedFury]

Forgot to mention, my case sits right next to my monitor with lots of space around it so airflow around the case isn't an issue.

I guess I'll have to experiment with the 2 back fans and see what gives me better case temps ( which will be easy with those snap in fan holders! ).

I'll have to post back once I get a working motherboard from NewEgg ( hopefully by the end of the week ).

The way I'm looking at it is that most cases are designed with the In, Up, and Out approach like a straightened "Z". Air in the front bottom, out the Rear Top.

I'm trying to see a different Jetstream through the case. More along the lines of an upside down "?" Where you have 2 levels of cold air coming in. The lower level hits the PCI/AGP cards, the Upper level hits the CPU/HDD and everything gets pulled up and out past the PS and the CDROM drives. Since there is 160mm of air moving equipment on each "level" and 200mm drawing air out of the case, the Ambient case air temp should stay relatively low even once it hits the upper atmosphere of the case where it would technically be the hottest. Since the PS is the only device that high that constantly produces heat, the fan in the PS pulls enough air to keep the PS from overheating.

Now, is this a legitimate theory, or am I just a deranged little man who's had too much time on his hands this weekend with the wife away on a trip?

[The Terk]

its kind of like the conservation of momentum, but with air... air in = air out. basically: if you have 2 fans blowing in, u need 2 blowing out, two intakes in front and two exhausts in back. you really need a psu that has 2 fans so that it acts as an independent system from the rest of the case. The addition of other fans is only needed if you need to draw in air from the outside (or remove direct heat from a full case) to add the extra cool air

This also draws into the room temp, because you could have the best airflow ever, but if your room is 90 degrees, all you are drawing in is warm air, and thats the air trying to cool off your parts... negative productivity!!!

this of course is my opinion, not an actual physics answer (which i can get in a few years) but it seems like common sense...

[cstierhoff]

One thing I have noticed when desinging the air flow in the cases I haved built and then saw the cases a year or so later.
I used to be concerned about having a greater airflow out of the case than there was inflow( i used the cfm ratings for all fans as a guide) it seem when there was a greater outflow of cfm there would be alot of dust collected in and around all cracks in the case and around the Rom drives and floppy drive or anyplace air could get sucked in.

Now to keep the case from sucking air in in any possible crack I make sure I have at least 50-75 more cfm coming in than going out. I guess you would call this positive air pressure in the case instead of negative air pressure. Movement of air inside the case is also important but quantities of cfm in and out needs attention also.

My 2 cents,
cstierhoff

[frostDA9]

Well I haven't had mine for long, but from what I can see compared to my last case, I think a good setup is: 2 medium CFM fronts, a low CFM top rear, a high CFM lower rear, and the PSU.
The low CFM top rear is so it won't pull too much air away from the PSU fan, which can draw hot air almost right off the cpu.
The side fan on my case disrupts airflow but cools the GPU directly....the verdict is still out on whether is a pro or con.
I'd try to create a vacuum no matter what, so that air is drawn out actively instead of just pushed around inside the case.
In any event, I'll be interested to hear what you settle on

[The Terk]

Originally posted by frostDA9
I'd try to create a vacuum no matter what, so that air is drawn out actively instead of just pushed around inside the case.

not to be mean or anything, but if it was a vacuum, there wouldnt be any air!! lol, i know what u mean, but it just sounded pretty funny

[Telexen]

You can't take just one method to it though. You have to use a combination of bringing cool air in and blowing warm air out