Overclocking

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Overclocking is the art of getting your CPU to operate at a faster rate than that for which it was designated!

What is overclocking?

Quite simply, overclocking is changing the settings on your hardware to make it run faster than the manufacturer intended. All hardware has a certain band (area) of speed that it was designed to run in. Therefore, overclocking pushes the hardware past its safe design limits.

Many parts of the system can be overclocked, but the processor is the most common. Most think that it is designed to run at one speed and that it can't change. But, this isn't really true. Processors are designed to run at different speeds, just like the other hardware. This way, it can work with a variety of systems. Besides, chips are often labeled slightly lower than their actual speed so that the manufacturer can guarantee it will work at that speed.

The actual speed of the processor is controlled by switches settings on the motherboard or software controlled switches in the BIOS. These switches control the bus speed and the processor speed. The reason for this, is so one board can operate a number of processors with different speed settings.

How do you perform overclocking?

All over the Internet, overclocking is made to sound so easy anyone could do it. And, in effect, it is easy, but only when it works. Furthermore, it should be noted that overclocking often voids your computer's warranty. Also, you may not have much success. Some chips and can be overclocked better than others, and it has nothing to do with the brand. It depends on the chip itself. Some motherboards are better than others when it comes to overclocking.

Given the fact that we have the Internet and that a lot of people spend considerable time on writing and publishing a lot of useful information, I suggest that now is the time to search for articles relevant to what you want to do. Do not stop searching and reading until you feel confident enough and have enough information to complete the task you have set yourself. Make sure you understand! It is even better if you know the make and model of your motherboard. You might even be lucky enough to find a page dedicated to overclocking your board and processor.

Below are some OverClocking Links to start you off with. If you still can't figure it out, you could always ask a question in one of the dedicated overclocking discussion groups, such as alt.comp.hardware.overclocking.

Anyway, back to the issue......

Probably one of the most confusing things to a beginner is this thing about multipliers and bus speed, actually called the 'Front Side Bus' (hereafter referred to as the FSB) speed. Lets say you have a nice 1.6A P4. (Historically this was one of the best CPUs for overclocking). That P4 has a 100MHz FSB speed. The FSB speed is the speed at which information is shuttled across the motherboard.

This FSB speed has a direct effect on the speed of our processor through something called a multiplier. It just so happens that the multiplier for a 1.6GHz P4 is 16. The reason behind this is quite simple...

16 (multiplier) times 100MHz (FSB speed) = 1600MHz = 1.6GHz

Do you understand? I thought you would!

Now that you know what a multiplier is and what your FSB speed is, lets think about how to make our P4 faster... For starters we could increase the multiplier! You see... if we changed our multiplier from 16 to 17 that would increase the core clock speed of our processor to 1.7MHz!

While this is a logical enough assumption, this setting will not allow you to overclock your Intel processor. Unfortunately The Multiplier on Intel Chips is LOCKED! It cannot be changed in the BIOS, or anywhere else for that matter, so that is a moot point. So, set CPU speed to the actual speed of your processor. In other words, to 1000 or 1600 or 2000 MHz - basically whatever your processor actually is. However we can change the FSB speed.

Ok now lets pretend we still have that 1.6GHz P4 with the 100MHz FSB and the multiplier of 16. If we increased the FSB speed to lets say 133MHz that would increase our core clock speed to 2128MHz!!

There is a drawback in having to overclock the CPU in this manner: The PCI BUS (your sound cards, network cards, hard drives and possibly your video cards) all sit on the FSB. When you overclock your CPU, you overclock everything. Even your AGP PORT for your AGP card is set to operate at a fixed fraction, (2/3 or 1/2), of the FSB.

Here's the first place where your motherboard will come through for you: It allows you to set the PCI clock frequency to a different and lower frequency than your CPU. This is most often done automatically for you; usually between 31 and 41 MHz - depending upon the FSB speed you select. On some boards you can set the PCI speed to Fixed, so that it will always operate at a default frequency.

At one point or another you will hit a limit which you cannot overcome without adjusting the Vcore or voltage level in the CPU. This is called upping the core-voltage. Just about anyone who overclocks anything knows that, often, an extra bit of voltage will help a component run at speeds it wouldn't before. For an in depth explanation, have a look at Dan Mephams' article Upping Vcore, CPU Overvolting Explained. Personally I will not go that far, as I then have to embark on project entailing additional costs for specialized cooling, heatsinks, fans, etc. But you are the one to decide where you stop, it is your money!

You should note that increasing the voltage beyond specification can and will prove hazardous, if proper care is not observed. More voltage and higher speeds mean more heat, so if you plan to increase the voltage on anything, make sure you have excellent cooling.

Don't be too quick to plug in a voltage and multiplier setting you read somewhere. Always see how far you can go with default voltage and move in the smallest possible increments.

A word (or two) of warning

No two computers will overclock the same, even if they're identical. Just because "Joe Overclocker" is running his chip at two Zillion MHz, does not mean that your CPU will be able to handle the same. Often, several different factors (including luck) allow some systems to overclock more than others. There are absolutely no guarantees in overclocking. Despite your computer skills and knowledge, you are dealing with random chance to a degree.

There is a risk of damaging components when overclocking. However, if you use common sense and follow some basic guidelines, then the risks range from considerably lower to nearly non-existent. Too much heat and too much voltage are the most frequent methods of frying components. Overclock at your own risk! Should you choose to do so, it is your decision.

Make sure you have good cooling and watch your CPU load temperatures like a hawk. The better motherboards will have temperature monitoring capabilities that can be read by suitable software (see the paragraph about tools). Download, install and use the tools before you start to overclock!! It is often too late to do this after you've hit a problem.

Always disconnect the power plug when you work with the hardware components. And always touch the metal part of the case before you touch anything inside. Be careful, very careful!

Overclocking procedure

The first thing you do is to make sure the computer runs stable at the default settings. Even though the objective is to find the highest, stable CPU speed the board can run at, always start out with the default settings. This not only makes sure that the board is in working order, but also gives you an excellent reference base-line to work from.

This is also the time for burning in the new computer. Burn-in or stress testing is a process by which you subject your computer to heavy usage. Most sites recommend at least a week. Electronic components usually fail early on, so by burning in the computer now, you can reasonably sure you've got a good motherboard and CPU. That is one less variable to worry about.

The primary reason to stress test a machine is to ensure its stability under extreme circumstances. Sometimes, there's also a burn-in effect whereby a machine actually becomes more stable after being subjected to prolonged stress testing. After strenuously stress testing the machines for several days (or sometimes weeks), the machine can become stable at its stock voltage without extreme cooling.

There are several ways that you can do this. You don't need to run all the tests, but it doesn't hurt. Which tests you run is entirely up to you. Use one or more of the following: memtest86, Prime95, Super Pi, and Sandra. See the paragraph on "Useful tools for OverClocking".

You are now ready to start the actual overclocking. Start or restart the machine. Hit DEL, or whatever key you use, to get into the BIOS. Find the page where you can set CPU speed, set this setting to manual.

Then look (usually just below your CPU speed setting) for a setting that says, System/PCI frequency (MHz) or, CPU host /pci clock or something related to one or both of these titles for this setting. The exact title varies from motherboard to motherboard. But they all do the same thing: Overclock you computer! For best performance, you want to find the highest FSB and CPU speed that you can run on your system without any problems.

Adjust this setting upwards very conservatively, basically increase the front side bus (FSB) speed a little at a time, then test for stability. Please heed my words: Adjust this setting only a few notches upwards, then Save and reboot. Once your at your desktop in Windows, check your temperatures, see tools. Repeat until it becomes unstable.

After each step of the overclocking process, thoroughly test your computer system for stability. Run the tools below for a long time. Monitoring temperatures and testing for stability is critical during all phases of overclocking.

If the computer won't boot, crashes, freezes up, pops up error messages or gives you the dreaded Blue Screen Of Death (BSOD), then it's unstable. You now have two options:

  1. Raise the voltage one notch at a time until it becomes stable again (check CPU load temps each time).
  2. Tell yourself that this is the upper limit, turn the settings down a few steps and live with it.

If you are going further and raise the CPU core voltage, be very sure that you know what you are doing. For safety's sake, don't raise it anymore than 10% to 15% above default. Also be sure that the system is cool enough.

  1. You will need to protect your gear, add cooling and modify the relationship between your CPU, RAM and motherboard settings. Check any OverClocking web site for articles on these subjects.
  2. Really understand your motherboard and BIOS by studying (not just reading) your manual.
  3. You will need detailed and specific advice as can be found in overclocking forums. This is the best possible preparation for dealing with problems you will encounter overclocking your particular CPU on your particular motherboard.
  4. Be prepared to spend quite a lot of money :)

OverClockers often use some of the programs listed below. You should download, install and use them before you start overclocking your system. WCPUid, Sisoft Sandra, and a Motherboard Monitor are a good start.

Overclocking tools

WCPUID 
WCPUID is the program that displays the CPU information of your personal computer. Shows Frequency, Multiplier, Chipset Information, etc.
SiSoftware Sandra 
SiSoftware Sandra (the System ANalyser, Diagnostic and Reporting Assistant) is an information & diagnostic utility. It should provide most of the information (including undocumented) you need to know about your hardware, software and other devices whether hardware or software. Sandra is also a very comprehensive benchmarking tool, it compares how your system rates along other top systems, and lower end systems. Sandra provides similar level of information to Norton SI, Quarterdeck WinProbe/Manifest, etc. It is a native 32-bit Win32 application.
Motherboard Monitor (MBM) 
Motherboard Monitor (MBM) is a tool that will display information from the sensor chip on your motherboard in your Windows system tray. MBM supports a wide range of Chipsets & Sensor Chip combinations.
Prime95 
Prime95 is part of the GIMPS program that is involved in the search for the very rare Mersenne primes. The very useful, for overclockers, feature of Prime95 is the Torture test, as this does a lot of very intensive work that can really help stress systems.
SuperPI 
SuperPI calculates the number PI to 1 Million digits in this raw number crunching benchmark. The benchmark is fairly diverse and allows the user to change the number of digits of PI that can be calculated from 16 Thousand to 32 Million. The benchmark, which uses 19 iterations in the test, is set 1 Million digits. Lower numbers denote faster calculation times (seconds), and hence, better performance.
memtest86 
This test is quite good, since its requirements are very simple. As the name suggests, it aggressively tests all of your system memory to make sure that there are no defects with your RAM. This is primarily a way to determine if you have dodgy RAM. Its use as a burn-in tool is simply a side effect. Since it boots off a floppy and contains everything it needs, you don´t even need to set up an operating system to run it.

See also

External links