Crash-Proof Your PC!

An easy guide to better case ventilation


Is your computer restarting in the middle of a gaming session or is your hard drive crashing too often? There may be a zillion reasons as to why that is happening but the biggest culprit most of the times is overheating i.e. your processor or your graphics card gets so hot that it has to shut itself down to prevent burning out. Again, there can be different reasons for overheating like a thermally inefficient architecture of the product itself (The Prescott range of Intel processors would run very hot and unless you had a good case with excellent ventilation you were sure to run into problems), a bad cooling set-up (heat sink and fan), this happens a lot in case of graphics cards where the board manufacturers use a substandard heat sink-fan assembly to cut costs and lastly and most importantly bad case ventilation.

We have to remember that the temperature of the components is directly proportional to the case temperature, (also known as ambient temperature) and higher the case temperature, higher would be the temperature of the internal components like the processor, motherboard, graphics card and hard drive. For example, a ceiling fan in a room with cross ventilation will be able to cool the room faster than the same ceiling fan in a room with little or no ventilation. So the bottom line is, we have to ensure that the case is well ventilated. And that’s exactly what we are going to show you in following article using simple and cost effective methods.

Before we start we would like you to understand these points. A processor when not doing much work is in a 'idle' state. When its doing heavy duty work like encoding a movie or playing a game, it would be in the 'load' state. You can get an idea of how much work the CPU is doing by looking at the 'CPU Usage' graph under 'Windows Task Manager'.

Crash-Proof Your PC!

A processor runs at a higher temperature in load state. Generally under ideal conditions the processor idles at 35-45 degrees and goes up to 55-60 degrees under load. Similarly for a graphic card, the card is under load while playing an intensive 3D game like F.E.A.R or Far Cry. Under ideal conditions a graphic card would generally idle at 50-60 degrees and go up to 75-80 under load.
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Step 1: Get the right case
Most of us select a case only on the basis of looks. Two factors which are very important while purchasing a case, is the material its made of and the number and sizes of fans it can house. An aluminum case dissipates heat faster than a steel case. For example Antec’s SuperLanBoy case is an all aluminum case. The case should have the provision to mount at least a 80 mm fan in the front and a 120 mm fan at the rear. An 80 mm fan is the size the of regular cabinet fan you get in your local computer store. 120 mm fans are larger than 80 mm fans, they move more air and are less noisy as compared to 80 mm fans.

By moving air we mean sucking air into the case or pushing air out depending on how the fan is mounted. If you are confused you can just place your hand close to the fan. If the air is blowing onto your hand the fan is mounted to exhaust air out of the case. If you don’t feel anything, then the fan is pulling air into the case.

Not all 80mm or 120 mm fans move the same amount of air. The amount of air a fan can move is mentioned in the form of CFM i.e. Cubic Feet Per Meter. The generic 80mm 'cabinet' fans you
get for 50 rupees don’t have the CFM mentioned. Its only with known brands like CoolerMaster, Vantec, Antec, Sunon, Panaflow, etc. that you have it. Higher the CFM, more is the amount of air the fan can move.

Another factor one needs to consider is the how much noise the fan makes. You wouldn’t want your case to sound like a jet engine. The noise emitted by the fan is given in dB under specifications by the manufacturer. Towards the end of the article, we show you how to build a silent system.

For now lets look at the various different fan arrangements we have in cases and our opinion on them.
Case type 1:

The above diagram is an ideal arrangement. Even though this is an ideal set up, there are two other things which come along with it - dust and noise. Remember the fans make a whirring noise when they rotate and too many of them can get a bit too noisy. So only if you are in need of a very good cooling set up and don’t mind the noise and the dust that comes along, you can go for it.
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Case type 2:

We personally like the above setup best. It has one 120 mm fan as intake and another one as exhaust. We like this set up since it has only two fans so lesser noise and since they are 120 mm they move more air. Though cases with such an arrangement, especially the front 120mm slot are slightly on the expensive side. Antec SuperLanBoy is one case with a similar set up.

Case Type 3:

The above arrangement is the bare minimum we would recommend. Most entry level cases come with two 80mm slots. Make sure you mount the fans and orient them to intake and exhaust.

Many of our users complain that the inside of their case gets very dusty. Of course you cannot eliminate dust altogether but by following these simple laws of physics you can tweak your setup.
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Step 2: Decide the pressure Set-up

Negative pressure Set-up

This happens when more air is going out of the case than coming in i.e. in the following example (it applies to any kind of set up, in cases with more than 2 fans, you add the CFM of the fans oriented in a particular direction) more air is exhausted by the rear fan than what is pulled by the front fan. This builds up a negative pressure. To compensate for this, air is pulled in from all the openings in the case, thus bringing in cool air. Though this is the best set up for cooling but is more susceptible to dust since air is coming into the case from the fans as well as from small crevices and openings. If your PSU has a dual fan set up wherein air is pulled from the case and exhausted, also add the CFM of the PSU’s fan.

Positive Pressure Set-up

In this set up more air is pulled in the case than what is exhausted. Though not as efficient cooling wise as the negative set up, its not all that bad either. The point to note here is that in a positive pressure set up, the air pulled into the case would be only from the intake fans. This is an excellent mechanism for cutting the dust entering the case. To go a step further, you can add a filter to the fan, similar to the one in an air-conditioner. You can easily source it from any hardware store and screw it between your intake fan and the case.
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Cable Management
After you are done with selecting the right case and the kind of pressure set-up, you need to do some cable management. Unused power cables and fat IDE cables can come in the way of smooth flow of air. Again its very simple and doesn't require to rack your brains. The diagram below will guide you through.

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Practical Tests
Lets run some practical tests. We used the above mentioned set ups and checked the temperature at idle and load conditions. The temperature of the case (ambient temperature) was measured using a temperature probe placed towards the top of the case, since hot air becomes light and travels to the top of the case. So its hottest at the top.

Processors and graphics cards (most of the them, barring some entry level cards) have a temperature diode on the chip. You can view the temperature of the components by using a software program like Everest.

We subjected the system to load by playing Need For Speed: Carbon.

Test System
AMD 3200+: Socket 939
Asus A8N-E
Corsair 512x2, 400 MHz DDR RAM
XFX 7600GT PCI Express
Seagate 120GB SATA

All temperatures are in Degrees 120mm front intake & 120mm rear exhaust
(Idle / Load)
80mm front intake & 80mm rear exhaust
(Idle / Load)
No front intake and 80mm rear exhaust
(Idle / Load)
Case Temperature 31/35 33/38 35/42
Graphics Card 52/71 54/77 56/82
Processor 39/46 42/51 43/55
Hard-Drive 38/42 40/45 40/48

Silent Systems
Along with the fans comes noise. C’mon you wouldn’t want your computer to be whirring like a jet engine in the dead of the night. Its very simple, if you want a silent fan, you will have to trade it for lesser CFM because, more CFM comes with more RPM (Rotations per minute) of the fan and more the RPM, higher is noise level. Though there is a series from Vantec called the ‘Stealth Series’ which offers low noise levels. The 120 mm fan gives out 28 dB of noise with a CFM rating of 54.

Conclusion
At the end of the day, you should implement all the steps and play around a little to see what suits you the best. Lesser temperatures means system stability and a longer life span of products.