Having correct airflow through your PC case is critical to your system running properly. Heat buildup in a computer case can cause lockups, slowdowns and even shutdowns. You should carefully consider the direction of the air when building a PC or when modifying an existing computer.

Which way should the case fans blow?
The CPU fan attached to the heat sink should blow down onto the heat sink and processor. Fresh air can be pulled in this way, but you will want additional fans installed to help bring cooler air into the case. An 80mm case fan installed in the front of the computer pulling air in will help the processor run cooler. You may also want to add an additional fan at the rear of the PC that blows the air out of the back. This additional fan in the rear may not be necessary if the power supply has an intake fan inside the case that can pull that warm air out.

Improving airflow in the case
You can greatly increase the airflow through your PC by swapping out the standard, flat IDE cables with the rounded type. Because the rounded cables take up less space, air can easily move through the case without being trapped inside. Depending on your setup, you can also rearrange the power cables so that extra wires can be coiled and tucked away near the top.

Balancing PC airflow
Another thing to consider when adding fans is the effect it will have on the interior of the case. If you have a lot of fans pulling air in and not enough moving air out, the interior of the PC will become filled with hair, dust and other debris. You should also not hear one fan working harder that the others. This means the airflow is not balanced properly. For instance, if the rear case fan makes a whirring sound every few seconds, this could indicate there is too much air trying to escape and it cannot keep up.

Whatever you do to improve airflow, you should open the case after a week to make sure everything is clean. You can also download monitoring tools to test the case and CPU temperatures before and after to make sure air is circulating properly and keeping the CPU cool.

There are a few computer casings which are designed for good airflow.

For good air flow, you need to have one fan sucking in air and another blowing out. If your case have a lot of holes, it may be good considering having the fans blow air out as air slowly coming in from many directions will prove to be cooler than air forced in from one port.

Many though have fans at the side blowing towards the motherboard which would also cool down the cards connected to it.

Aluminum casing also proves to be a big factor in cooling down the air inside the case. Using SATA drive will also affect good airflow because of the thin cabling it uses compared to IDE. And mind you, the hard drive also needs good airflow so air has to flow through it.

Those few brands that offer aluminum casings that I can remember are:

- Lian Li
- Ultra
- Thermaltake

Your choice.

I have three fan gaps, one is unused, one is out by the PSU, and one is weakly in. A few internal fans, over CPU and something else (not gpu, that's integrated). Should I change something, like make all case fans go out?

Thank you for the information, I have recently swapped cases, and have been meanig to go back and address fan concerns, but until now it slipped my mind...... Hopefully ill get it done before i forget again

My computer case seems to be pretty good but I can't tell if it's running hotter than it should. All I know that when it gets over about 27 C a second fan kicks in and is quite noisy. When this happens I either put on the A/C or switch off my PC till the weather cools off a bit.

After reading the above comments about keeping a pc cool and airflow considerations, I know and admit I don't have the best setup. First of all the case is like 10 years old. It is some sort of pressed metal/aluminum. Though I may not be the aluminum like today's PC's but this case can probably take a bullet. It has an ugly off white paint job which is getting yellow with time.

There are some vents in the front plastic benzel and a 2"x10" grate like openings along the whole length of the back side. There is just a little 2"x4" rectangle on both lower side panels. The original fan for that mounts on the inside front is big, awkward and noisy. I unplugged it at first cause of noise concerns when listening to music and gaming, but now I removed it cause of possible air flow concerns and the noise is probably cause of bad motor or lint/dirt in the motor can't be clean.

Last year I threw in a new motherboard with a Core 2 Duo setup. The power supply I'm sure barely meets the standards. What's awkward about the power supply is that it blows air inward from the outside. During the mother board installation the manual made certain references to a some pc case standard about installing in a case with a baffle which allows direct air flow across the processor. I don't recall what that standard was. Since I know my tank does not qualify I had to make some minor adjustments.

At the time I was drinking some power aid (32 oz. sports drink) and thinking was I can do about this. I then did some measurements on the proper location of where the processor would be in relation to the case's side panel. I traced it the side panel and went outside with some power tools. I drilled some new holes in the case used the sports drink container as the airflow baffle. While I was at it, I then drilled as much holes as I could into the bottom side panels - to bring in that cool air from outside the case.

That's how I modified my ugly case to run my new board. I guess it works fine but I'm sure if I had a something like a mechanism with an external HEPA/3M filter and an internal blowing fan mounted with the sports drink baffle, that would take care of my processor concerns.

Has anyone done any case altering modifications that help with overall cooling with attention to keeping dust and lint out? I'll try to post some pic's when I have a chance.

Hello!

The concept of a Proper Airflov Through A Computer Case is similar to a room's exhaust system. Cold air has higher dense, just like when you open your refrigerator, the cold air comes out below the door. for my experience, when applying it on a PC, it it much better to put many in-haust (in-take residing below the PC case) air than an exhaust one. since air naturally goes out the PC case. also consider the placement of your PC as it has an advantage of getting cold air near the floor, but the best place for a PC is on the table. The table area doesn't eat much dust and can absorbs levels vibrations which extends PC life more longer from maintenance. it is based on the experience/problems I've analyze from my work. the PC airlfow system is identical to a house's exhaust or air system.

just fine
Proper Airflov Through A Computer Case

mine was simply good in terms of proper ventlation,

I have 120mm fan in front that blows air in and

a double 80mm that blows out air in the rear side.

I got 1 80mm on the upper side panel that blows air in which is parallel to my custom cpu cooler(not from intel)  that would bring cooler air into the heatsink.

and on the lower side panel has 1 80mm also but blowing air out which is to cool down my PCI-e video card.

 would you agree on this..

pls do comment on my custom fan set-up.

thanks. :)