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Troubleshooting overclocking problems ( Part 1 )

The mere mention of the word overclocking brings different images to mind. There are those who are the "hard-core" in the world who would never run a CPU at its rated speed if they could help it. Then come the "hobbyists" who would like to try it but may not know how. Last of course come the "masses" who have no concept what overclocking is much less would they like to try it less they offend the x86 gods. While the different views of overclocking are easy to categorize obtaining good information to help your overclocking project is much harder to find. The net abounds with wild stories of amazing people who can overclock a toaster oven to run Quake III at 1280 x 1024 with 60 fps but rarer is the person who can actually explain in detail how they achieved the amazing feat. This guide is not meant to be the only source of data you should consult nor will it obtain all the information necessary to complete your overclocking goals. It merely will help you to troubleshoot problems you may be experiencing with your project and give you solutions you may not have considered previously.

Origins of Overclocking

It would be naïve to think that overclocking is a new concept. The idea of increasing output from any machine with little improvements is nothing new. A simple machine such as a lever can be fine-tuned when its fulcrum is moved to a more optimum position. This allows more work (output) to be performed with the same amount of effort (input). Obviously the automotive industry is no stranger to these ideas. How often do we see improvements in a cars power ratings year to year with only minor reengineering of its components?

I have seen computers that have 20 MHz 386 processors overclocked to 25 MHz however when Intel released the 486 platform there was finally a computer worthy of overclocking. The 486 family rapidly increased in clockspeed until the range it was available in became quite impressive (25 MHz to 100+ MHz). A new concept was introduced with the CPU multiplier. It was basically a multiplier that allowed a higher clocked chip to utilize the slower bus speeds of the other chips available. For example: a 66 MHz chip utilized a 33 system frontside bus with a multiplier of 2 while a 33 MHz chip utilized the same frontside bus with no multiplier. Intel had created a workaround for the problem with slow bus speeds that actually benefited the overclocking community. At that point the accommodations for overclocking were already present on the motherboard. I have overclocked 25 MHz chips to 33 MHz and have seen systems with 66 MHz chips running at 75 MHz. At some point people began to overclock their 486 chips to the point they realized they were damaging them from heat, thus forcing them to reconsider their cooling requirements and strategies. The basic techniques of overclocking have not changed since then and consist of either modifying the multiplier or frontside bus that the CPU utilizes and controlling the subsequent increased processor heat. This guide will apply to almost anyone but if you own a 486 based system to the newest systems you will benefit the most (sorry 8086-386). Owners of chips made by manufacturers other than Intel should remember that your chips meet the x86 standards so this applies to your chip(s) too.

Fundamentals of Overclocking

As I stated before the basics of overclocking deal with either changing the CPU multiplier or the frontside bus of the system. Intel saw that the manipulation of CPU multipliers was leading to remarked chips entering the market so now all Intel CPUs come with a multiplier that cannot be manipulated. This means that for most of us the only modification available to increase system performance is to raise the system frontside bus speed. Definitely gone are the days of the 486 and Pentium that could accept changes to both their frontside bus and multiplier to gain increases in speed. This couldnít have hurt Intelís profits either since making CPUs harder to overclock forced the consumer to purchase upgrade processors rather than overclocking their own processor. As CPU speed ratings have increased so has the quality of the CPUs themselves. A 233 Pentium MMX could never be expected to obtain the dramatic increases now available to us simply because the CPUís quality will not allow it to. Intel needed to increase quality in their chips to continue offering new products and that has directly benefited the overclocking community. If you own a more recent CPU then your chances at success are higher due to these quality issues.

If you have seen all the testimonials on the net that people post about products such as heatsinks and case fans you have probably realized that one of the most important things you can do to increase your overclocking success is to reduce the temperature of the CPU. Like anything electronic the reduction of heat increases reliability and may actually allow you to hit speeds that would be unavailable to you without extra cooling. Also be aware that you may have to increase the quality of signals that travel through the tracings of your CPU by increasing the amount of current that these signals use. Obviously that is one of the chief reasons people damage their CPUs as they become overzealous in their approach. That is why you often see an article like this accompanied with a warning. My warning is simple: I am not responsible for any damage you cause your processor. Be sensible with your project. I will give you several tips to help you reach your goals but if you donít approach your project with patience and the realization that you may never reach these goals then you may in fact damage your processor, system, or its components. A damaged processor is actually very rare since most systems will either work at the higher clock speed or wonít but careful attention to cooling will always be necessary. That is why I will tackle cooling problems first since that is probably the most common reason attempts at overclocking fail. The tips are listed in no particular order. Consider which will help you in your situation (overclocked or not):

  • Use heatsink compound between your heatsink and CPU. Very few systems actually come with heatsink compound on the CPU. It will fill the irregularities on the surface of the CPU and heatsink to increase the transfer of heat.
  • Apply heatsink compound between the CPU and heatsink sparingly. More is definitely not better in this situation. You should feel the CPU and heatsink scraping on each other when you move the heatsink around. The heatsink should not be floating above the CPU on this goop.
  • You can never have too much cooling especially where the CPU is concerned. The heatsink and fan that came with your CPU was probably designed for its original speed rating. Consider upgrading to a better heatsink/fan if programs lock up more than they did before you overclocked the CPU. Better heatsinks will allow you to reach higher clock speeds (if your processor is able to).
  • The truly radical may decide that standard heatsinks are not enough for them. At that point it will be time to consider refrigerant cooling, peltiers, and water-aided cooling devices.
  • Make sure there is adequate airflow being pulled into the case as well as being exhausted from the case. Many cases may have either an intake or exhaust fan but rarely do they have both. A $10 case fan can be used for intake or exhaust purposes. The more the better.
  • You can cut holes in your case to accommodate more intake and exhaust fans. A blowhole (exhaust fan mounted to the top of the case) is a very efficient.
  • If your case is too small to accommodate more fans remove the covers on your case for all the PCI and ISA components. This will allow as much air to circulate as possible.
  • Keep your heatsinks and fans dust free in order to maximize cooling.
  • You can fashion a simple airfilter from the thin foam material that surrounds most new components (such as motherboards) when they are new.
  • Your power supply is not an exhaust fan. Most power supplies run at approx. 70% thermal efficiency. That means that 30% of the heat generated by your power supply is entering your case.
  • In severe conditions you can remove the cover from your case. This will let you know if your stability problems are truly heat related.
  • Remember that heat rises. Donít place your exhaust fans at the bottom of the case. Likewise never place intake and exhaust fans next to each other as this will cause the cool intake air to be immediately exhausted before it can travel to other areas in the case.
  • Keep intake fans low if possible. A combination of a low intake fan and a second intake fan higher in the case may neutralize hot spots and create large cooling increases.
  • Full towers tend to have their power supplies mounted towards the middle of the case. Look for one that has an exhaust fan opening either beside the power supply or above it. An exhaust fan above the power supply is more desirable as it will remove the heat trapped at the top of the case.
  • Route your cables so that they do not block the natural airflow up and out of the case.
  • Mount your 5.25" components as high in the case as possible as they tend to intrude into the airflow within the case.
  • 7200-RPM harddrives run hotter than 5400-RPM drives. Consider directing a fan at a hot harddrive or even buying one of the available harddrive cooling devices that use multiple fans and/or heatsinks.
  • A video card running at high frontside bus speeds will run hot. Consider mounting a fan and heatsink on a chipset that does not have one. You can use parts leftover from replaced CPU heatsinks. You can also mount heatsinks to your video card memory.
  • The truly hardware inclined can remove the fans from old power supplies as they make great intake and exhaust fans or they can be used to direct air at specific components.
  • There are software cooling aids such as Rain and Waterfall. They allow the CPU to cool down by not forcing it to run 100% when it is sitting idle.

In the second installment of this article we will begin to look at solutions for problems you may be experiencing with your installed components, memory, and specific techniques that may get you a little more processing power. Those of you who have never attempted to overclock your system will find the information in the next article to be interesting. Lastly we will cover overclocking strategies for specific CPUs. I recommend you review the above cooling tips and correct any deficiencies you find in your system before any attempts at overclocking. Obviously if you are experiencing occasional heat related problems they will be magnified when you overclock your CPU.







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