Wow, we've finally gotten to the meat and potatoes of this guide - the actual process of overclocking your processor. Well, shall we begin?
The first step in this process is determining what steps you will need to take to overclock your system properly. For the sake of some minor brevity, I will assume you are using an Intel Celeron/PII/PIII processor and a BX motherboard of some kind. These systems are the ones that are most commonly overclocked, and besides, overclocking the Athlon takes more than a little technical know-how, it also requires quite a bit of manual coordination. I will also assume you will only be using some form or relatively simple passive air cooling, as opposed to a Peltier or similar unit.
For an Intel based system, the first thing to check is whether or not you can configure the processor speed and internal voltage within the BIOS. Most newer motherboards, as well as most older ABIT boards, support "jumperless" configuring. If you are lucky enough to have such a system, your job is simple. All you need to do is raise the processor speed to what you want, change the voltage if necessary, and you're gold. If you have to deal with the jumpers, however, you've got a chore for yourself.
To change the computer's settings using jumpers, you are going to need your motherboard manual, or a copy of a jumper map for the particular model of motherboard. Using the jumper maps, determine the proper settings for the wanted processor speed and core voltage. Then move the jumpers on the motherboard so that they match the jumper map. To do this, you may need a pair of tweezers and a pen light.
Woo-hoo, congratulations, now your system is overclocked. But wait, that was too simple - what gives? Why did I write this huge guide about overclocking if the steps were easy as 1-2-3? Well, we aren't quite done yet.
The next step in this process is to attempt to start up your computer. The first test is seeing whether or not the computer will post. Posting is the process of the computer initializing the BIOS and loading up the system settings. If your computer won't even do this, there is almost no chance you will ever get it to run at the configured speed. Go back and lower the processor speed and try again.
If the computer did post, however, but it won't boot up Windows, you may want to try going back and upping the chip's core voltage. Take this as a word of advice though, make sure that you don't raise the core voltage too much - generally no higher than 0.3 V above default. If you go much higher than this, you run a serious chance of permanently damaging your computer.
Assuming your computer starts to boot Windows, but crashes before the system begins to settle down, you have two options as to how to deal with the crash. You can either go back and change the system's core voltage or you can add more cooling. That may include adding more case fans, installing a larger and more powerful fan/heatsink combo, or both. At this point, if you are able to do both, you may even be able to reach a higher speed.
Ok, your computer boots. Great! But you aren't out of the dark yet, because you still have to check and see if the system is completely stable.
System Stability Testing
There are generally two types of testing that I perform on a newly overclocked system. One is an intensive integer/FPU test which keeps processor utilization up between 95 & 100% for upwards of a half an hour. If the CPU passes this test, the overclock on the CPU itself is stable. However, even if the system passes that test, I still run a gaming test. The gaming test determines how well the rest of the system responded to the overclock (this is particularly important when dealing with non-standard bus speeds and out-of-spec RAM. Another test that I recommend, if you own the software, is the SiSoft Sandra benchmarks, or alternatively, WinBench 2000. Both pieces of software do subsystem specific testing - something that can be very important, particularly if you are trying to determine which pieces of hardware within your system are causing a failed overclock.
The intensive integer/FPU test is aptly named Stability Test and can be downloaded at www.tweakfiles.com. To use this test, you need to configure it before you overclock. This test will not only keep CPU utilization up at 100%, it will also make sure that the system isn't making any mistakes. This test only takes about a half an hour to complete and is definitely worth the time. If your computer doesn't pass this test, first try to either add more cooling or up the chip voltage a little bit and see if it works - otherwise drop down to the troubleshooting section for a few tips.
The second test consists of either using Unreal in Flyby mode with everything turned on (OpenGL), or using 3Dmark 2000 in loop mode (D3D). You really should only use 3Dmark 2000 if your system's OpenGL drivers are less than satisfactory. If you don't have a copy of Unreal, but your computer has a robust OpenGL driver, another alternative would be to use the Q3 demo with xero's 'monkeycrusher' demo. If your system passes both the integer and gaming tests, you have got yourself a stable system. Congrats.
Troubleshooting a Failed Overclock
To do this kind of troubleshooting, your computer has to be booted into Windows. If it isn't, take the steps outlined above to increase the stability of your system. Once you are in Windows, you will need to either install a copy of SiSoft Sandra or Winbench 2000. Then take each of the subsystem tests and run them separately from each other. Make note of which subsystem tests cause the system to crash, and focus on those parts of the system. That may mean adding a hard drive fan, some RAM cooling, etc. Once you have focused on all of the parts of the system that cause a crash (this may include the processor itself as well), go back and go through the system stability tests once again. If you can't get the system to pass the tests now, you may need to go back and lower the speed of the processor.
If you still refuse to give up on your 'golden' speed, however, you may want to try the following things:
- Leave your computer's case open
- Put your computer closer to your air conditioner
- Move your computer farther away from any heating ducts
- Make sure the computer has at least 6" of breathing room (15 cm) between it and anything else.
- Put the computer closer to the floor and farther away from anything that creates heat (your subwoofer, monitor, etc)
- Immerse your system in supercooled Jell-O gelatin and avoid eating it's jiggly goodness (yes, that was a joke).
Electrostatic Migration and Burnout
Electrostatic migration and burnout are the two things most feared by overclockers. Burnout is very simple - an excess of heat builds up within the processor, permanently damaging the hardware, making it unusable. This is the main reason why people make $75 Celeron keychains and other such adornments. Electrostatic migration, however, is just as deadly, and much less known. Each transistor within the chip's core develops an electrostatic charge over time, much like the way iron can develop a magnetic charge that will linger after any electric current has subsided.
Within CPUs, this electrostatic charge is a dangerous entity if it begins to affect the other transistors around it. That is why it is so difficult for computer companies to develop new chips - they must take into account the need for buffering room between the transistors within the chip. As a particular transistor's electrostatic field increases, it can cause damage to the other transistors around it. Electrostatic migration shouldn't be a problem for most overclocked processors unless you exceed the company's maximum core frequency for that particular model of core.
If you are exceeding the maximum frequency for a particular model of core, you need to be careful as to how long you have your computer running and how many consecutive hours a day you have it turned off. The longer you have your computer turned off at one time, the longer it will take for electrostatic migration to affect your system. You can't stop electrostatic migration from occurring, but depending on how you use your computer will determine how fast it will begin to take hold. Don't worry about it too much though, because even in the worst cases, it still takes a few years before it starts causing problems.
Overclocked Processor Lifetime
Worst case scenario for the lifetime of a non-burned out overclocked processor is over two years, while most processors will continue to function after five or six years. Unless you don't upgrade your system except when it breaks (this is very uncommon among overclockers and tweakers alike), you should never run into a problem with your processor's lifetime.
Effect of Non-Standard Bus Speeds
Non-standard bus speeds can have a variety of effects on various types of computer hardware. Hard drives can miswrite data, CD writers can create even more coasters than usual, CD-ROM drives can refuse to function, RAM can refuse to work properly, etc., etc., etc. Some of these problems can be fixed by adding some rudimentary cooling, but many of them are simple limitations of the hardware which will limit a system's overclockability. Keep an eye out for these things because they can cause serious problems with a system.
Most of these problems occur when using bus speeds that exceed the PCI bus frequency. PCI is intended to run at 33 MHz. If you set it to ove 40 MHz or so (using 83, 124, or 133+ MHz bus), there is a fair chance your hard drive will lose everything. See page 3 of the Hard Drive Tweak Guide for more information.
Alternate Overclocking Methods
There are, of course, other ways to overclock your system. Most notably, SoftFSB allows for overclocking your processor from within Windows without restarting. This is an impressive feat, but it isn't always as stable as changing the settings using the hardware. When you decide to use SoftFSB to overclock your computer, take the following precautions:
- Save before attempting anything
- Progressively overclock the system - go up one speed step at a time to make sure you don't inadvertently damage the processor.
- Run the stability tests to make sure the overclock was completely successful.
Well, there you go - you've got the low down on how to overclock a computer. If you are still not satisfied with the speed of your system, check out some of our other guides on how to overclock your video card or tweak your system. And as always, I'm available to answer any questions or receive any comments you may have.
