keeping that case cool
By Red Squirrel
The typical cooling method of a case is to have a fan blowing air in from the bottom front, and the air going up and sucked in to the power supply then out the case, also, this air passes by the CPU, which also (hopefully) has a fan blowing on it's heat sink
Modern CPUs require high-powered fans and also a heat sink to keep it a decent temperature; otherwise it will literally catch on fire! A heat sink is a simply metal fixture with fins, which the heat goes on and dissipates as the fan blows on the fins. Many different types of designs are always made and some are more efficient then others. The style now seems to be the "V type" which has the fins shaped like a V.
Air flow is the key to a cool case, you want air to easily go in, and go out, and you want the air to travel a wide area of the case to avoid having sections that never get an air change. With the law that says heat rises, this is usually done without too much thinking, simply by having a low intake (cooler air is going in) and a high exhaust (hot air is going out).
Some computers don't have an intake but only an exhaust, usually there is holes in the front so air can be sucked in, the problem with this configuration is less force pushing air in, this is called negative pressure, as the exhaust is basically creating a vacuum which is being filled by air being sucked in all cracks such as your floppy drive, card slots, front grid for intake fan etc. This also causes dust to get in all these holes, which is not a desired thing!
To avoid this, it is good to have a fan in front as an intake, however, not all cases are designed for you to be able to screw one in. However, you can always "fix something up", but however I won't cover that in this article, maybe in a future one. :)
Having an intake and exhaust creates a good air flow like described above, and also causes a better air flow with less static pressure. Assuming both the intake and exhaust move the same amount of air, the airflow is considered perfect. It won't try to suck air trough holes, and won't try to blow some out. However, if there is too much intake, it is better then too much exhaust. It is something to think of when putting fans. However, also keep in mind that other things such as the cables can distract air flow, make your cables as tidy as possible and make sure there's lot of room for air to pass by.
I want more fans!
If two fans is not enough for you, you can easily put more fans if your case has place, or if you want to cut the holes yourself. Make sure to plan where you think air will go with the new fan, for example, consider this new fan add-on where the top fan is blowing air in:
This would be a bad place to put a fan. Why? Because the air going in would most likely exit through the power supply right away, which would cause the intake fan to be forcing more air inside, and it would break the smooth airflow. The air going in the case would simply go out right away, and hot air would just "sit there" and exit through any other tiny holes from the intake pushing air. The air would eventually be changed, but it would be slow. This new fan would simply make things worse, and not better.
However, if you were to make that fan blow air out, it would help more, but unless you add another intake, it would create a negative air pressure.
This would still be better then the design with the air blowing in, however, since the hot air produced by the CPU would be going up, and exit through there, and as well as the power supply, and same with the rest of the hot air coming up from the motherboard, and the intake would be supplying cooler air.
To make this even better, a second intake could be added near the bottom. It would be best to have it side by side in the front, if possible, this all depends on the case, however. When choosing a case, this is something to consider very well. With this configuration, it would be double the air movement as the one with one exhaust and one intake. If you added another exhaust and another intake, it would triple, as long as the location would be well chosen. The main rule of thumb is to not put an intake close to an exhaust, as both fans will simply push each other's air in a straight short line, taking hardly any heat in the process.
Something to avoid as well is what is called an air "short circuit". This is when you have an intake pulling air from outside the case, and that same air is directly exhausted outside close to the intake and it would go back in the intake, go back out of the case and create a loop. Here is an example:
This basically uses electricity and produces noise for nothing. Not much is accomplished with this setup. It is always good to think outside the box and consider the outside air flow of the case, you want to make sure the air going in won't be air that just came out. Eventually no matter where you put the fans, it will happen. A perfect example is my room. I have no heat duct in my room since my dresser is on top, however, even in these long Canadian winters, my room is kept hot from air going in my PC and going out, so eventually this hotter air goes back in and warms up again. However having a short circuit makes it way worse as the air does not go anywhere else in the room to cool off a little.
Something cool to try is to duct the intake air from a cold location such as a basement, this would require some case moding and as well as some house moding so I won't go there. Love to, but this is not really my house... :)
A while ago heat sinks were mentioned; I will explain how they work. Heat sinks and heat sink fans are less of an air flow thing, it's more geared to cooling a surface that gets hot fast and requires to spread the heat on a wider surface (all the fins of the heat sink) and to have the fan blow on it to cool it off. Most metals are good heat conductors, this means that heat will "travel" on it.
If you put a rod of metal on a hot stove and hold it at the other end, it will eventually get very hot everywhere, not only where it's touching. If you did the same with a cement rod, it would take longer for it to come hot, and it would mostly get hot from the air around and not from heat conducting on it. This explains why the handle on your pots and pans is not metal, but a special heat resistant plastic.
Heat sinks are seated directly on the CPU which produces lot of heat that needs to be moved away fast, so it travels on the heat sink, and because there's a lot of surface from the fins, it has lot of room to travel to, and the fan "blows it off" as more heat is produced by the CPU and travels and the beat goes on.
Before, computers could operate with simply a heat sink, now, heat sinks are 10 times the size of before, and also require a powerful fan capable of moving air faster then most case fans! Even then, CPUs are sometimes hotter then they should. The material used for the heat sink makes a big difference, copper and aluminum are very good heat conductors, the fact on which is better is a debatable subject. If a wooden heat sink was to be created, it would not perform very well. Touch something made out of wood, and then something made out of metal, which is colder? Metal of course, it's because it dissipates heat better. Note that by metal I mean anything on the left of the "stair case" of a periodic table, and not metal as in steel.
A new technology, which is becoming more popular is water cooling. This works the same way as air, but instead, water is passed through tubes to "collect" the heat and bring it out of the case where it is then "radiated" off. Problems with this are reliability. If a tube breaks inside the computer – say good bye to your PC! Or if the water is cooled down (who would not be tempted to throw in some ice or something? :P ) it will cause condensation.
Cooling is a very vital aspect of computers these days and is sometimes overlooked. Having a cool PC will not only make it last longer, but also make it more stable.
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