Cooling

The biggest enemy of overclocking is heat. As I mentioned before, the CPU will develop more heat when running faster and we need to find a way to get rid of this extra heat.

I’ve seen some hilarious web sites where you can find info about water-cooling your CPU, cryotechnic setups, peltier cooling units and other hair raising scenarios. I will not even go there as it is extremely experimental and risky. We will use good old fashioned common sense and some fans. Again, we are not on a quest to get the fastest PC and therefore the right to brag how we are running our PC at 650 MHz (but fail to mention that you built a custom refrigerator as a case and spent 500 dollars doing so).

As a general rule, your PC should be located in a well vented area, not exposed to direct sun light. Don’t cram it in between the bookcase and the desk with less than an inch to spare on each side where it cannot breathe and you cannot get to it. Give it at least a foot on each side. Don’t put it underneath your desk next to that space heater either – bad idea.

For overclocking, we have to take this a step further. Air flow is what we will use to take the heat away from the CPU and out of the case. Open up your case and take a look inside. Do you see any fans? You should have at least two fans already in your case. One in your power supply and one on top of the heat sink on top of your CPU.

The fan in the power supply is supposed to take warm air and blow it through the power supply out the back of the case. Turn on your PC for a second, stick your hand right underneath the power supply (careful!) and feel which way it is blowing – in or out? If it blows into the case, you should change that because this introduces hot air produced by the power supply into the case. There are two ways of doing that:
One is to open the power supply and physically reverse the fan. But be extremely careful if you do this. Your PC should be turned off and unplugged for several hours because there are some pretty strong capacitators inside that store a charge for quite some time. If you touch those while still charged, your grave marker will probably have some reference to Kentucky Fried Chicken on it.
Another option is to replace the power supply with a newer model that blows out. But most likely you won’t have to do either as most power supplies blow air out.

Now we need to take a look at the heatsink and fan on our CPU. You do have one, right? This should be a metal part looking like a 3D comb with a fan on it attached to the side or top of the CPU depending on what CPU you have. A good heatsink is about an inch high and has at least one fan mounted to the top of it. If your heat sink is pretty flat and/or has no fan on it, you should get a better one.

Any decent PC store will have a nice selection to choose from. Make sure that you can tell the guy in the store what type of CPU you have so he can give you the right model. Again, the heat sink should be about an inch high. If you can get a model that has two fans on it, even better. For Pentium II and Celeron processors, these are available at any computer store. Also get some heat sink compound while you’re there. This is a paste to enhance heat transfer between CPU and heat sink.

Before you attach the new heat sink, carefully spread a thin layer of this compound on the CPU where the heatsink will touch it. Then put the heat sink on, but don’t secure it yet. Pull it off the CPU again – straight up, don’t slide it – and look for spots that are still smooth. They will need a tad more since they did not touch the heat sink. Once this is covered, put the heatsink on and be sure to connect the cable for the CPU fan either to a connector on the motherboard or a free power cable from the power supply.
This setup draws heat from the CPU to the heat sink which has a bigger overall surface to dissipate heat faster. The fan(s) will blow the dissipating heat away from the heat sink to accelerate this process.

Great. That’s done. Now let’s examine the air flow in the case. We already took care of the power supply fan. Now ideally, you should have two additional fans in the case. Look at the bottom front of the case. There might be a funny plastic contraption with no obvious purpose. Take it off and you will see that it is made to hold a fan. If there is no plastic contraption, you will see just four holes in the metal to mount the fan on. Measure the width between the screw holes so you know what size fan to buy.

Now look on the back of the case. If you have a mid-tower case, there should be another place to put a fan right underneath the power supply. If you have a full-tower case, there will be a place for a fan right above the power supply. Again, measure the distance between the screw holes and get a fitting fan.

Now the trick is this: The fan at the bottom front should be mounted to blow air INTO the case. The fan at the rear middle or top should be mounted to blow air OUT of the case as it sits higher up and hot air usually rises to the top. At least on this planet it does. The fan has usually a marking on it, a small arrow, that indicates the direction of air flow.

That pretty much takes care of the cooling. We should now have a nice flow of cool air through the case with fans exhausting the hot air created by the CPU, power supply, video card, drives, etc. without spending too much money. Even if you bought another heat sink for the CPU and two new fans, you should not have spent more than 35-40 dollars. If you want, you can add another one or two fans aiming at the video card and/or hard drives, CD ROM drives etc. In fact, if you use SCSI devices, you should do this, since they usually produce more heat than IDE devices

Now let’s move on to the actual overclocking process – increasing the speed.

 

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