Introduction to overclocking
From Overclocking Wiki
Overclocking is the art of pushing your computer to perform better than it was originally intended to. The term got it's name from the most common (and likely first) way to push your computer past its "limits", speeding up the CPU clock. Techniques like this allow you to get a high performance computer for pennies on the dollar or build a computer that exceeds the performance of the fastest pre-built computers you can buy.
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An Introduction
Reasons for overclocking
While people have many motivations for overclocking, their end goal generally falls into one of two categories.
To obtain more speed
The people who overclock for speed know no boundaries. These overclockers are here to make records, then break them. Money is no object, unless, of course, you have none. Even then it is only a minor setback. While people in this group are highly visible, their reason for overclocking is in the minority. Overclocking for these people is a hobby.
One such overclocker going by the handle 'duck' set the speed record of 7.658 GHz using an Intel Pentium 4 670 (Prescott). That processor normally runs at 3.800 GHz which means he more than doubled the speed of his processor.[1] To get these kind of results he had to use liquid nitrogen cooling (usually abbreviated as LN2) and run his processor at -192 degrees Celcius.
To realize better value
The people who overclock for value are interested in getting a faster computer for less. This group is about saving money, not spending it. They want to get their $200 processor to run as fast as the $400 one without spending $300 on some exotic cooling setup.
To give an example of how much money you can save by overclocking, it's not uncommon to see a new overclocked Core 2 Duo E6400 processor running over 3 GHz.[2] This puts this $200 CPU running faster than a Core 2 Extreme X6800, one of Intel's top of the line processors that cost $1000. Best part about this overclock is the fact that it was done on stock cooling, so you don't have to spend any money on fancy cooling solutions.
Origin of the term
The clock is a circuit in a computer that generates a regular sequence of electronic pulses used to synchronize operations of the processor's components. These rate of these pulses are measured in Hertz (Hz), or pulses per second. The rate of these pulses is called the clock speed.
In older processors, each pulse casuses the CPU to complete a single basic instruction. In more modern machines, several actions can happen concurrently during a single clock pulse. In either case, increasing the rate of the clock pulses will increase the rate at which the processor will perform its work. A machine that's clock is set over the manufacturer's specified limit is said to be "overclocked".
How overclocking works
To make a good product, a company needs to make sure their product does not fail. Often, if you run a computer part at its maximum potential for an extended period of time, it will fail. So to prevent product failure, the company doesn't sell their products at their maximum potential. Instead, they sell them at 80-95% of their potential. This prevents the user of that product from accidentally burning out the part. If you are careful, you can take advantage of this extra head room and push your computer to run faster. But, these incremental gains are boring and really don't save you much money, so what's the point?
Overwhelming success
Sometimes a computer part is so well made that being able to overclock it is almost guaranteed. This kind of success is commonly seen in CPUs. CPUs are not built to run at a given speed, instead they are build to have a given architecture. This architecture usually has some sort of code name. This code name is then marketed under a brand name. Several different architectures can be marketed under one brand name. An example of this is the Athlon XP line of processors, which was used to market 5 different architectures (codenames Palomino, Thoroughbred A, Thoroughbred B, Thorton, and Barton).[3]
CPUs of a given architecture are "printed" onto a sheet called a wafer. Tens to hundreds of CPUs can be printed onto one wafer. After the CPUs have been printed, they are then tested to see how fast they can run. These tests will be used to determine under what speed rating they are sold at. A given CPU architecture will usually be sold under 3-6 different speed ratings. These speed ratings are marketed in such a way so the company making the CPUs can make the most money. Some chips do so well in the speed tests that they are sold at a slower rate in order for the company to make money.
This kind of situation allows us to make those legendary 100% overclocks and make a $200 CPU run as fast as a $1000 CPU. One of the more widely known CPUs that did this was the Intel Celeron. Which is, incidentally, where overclocking really started to make a name for itself.
Overclocking and You
Should I overclock?
One of the more common questions asked is if someone should overclock their computer. The answer is NO. Overclocking can cause damage to your system and it will always void your warranty. It often causes your computer to behave erratically and crash. Unfortunately, overclocking is an art, not a science. There is no easy way to overclock your computer. What works for one person may not work for the rest. If you are willing to do the research and take the time needed to carefully overclock your computer, the benefits can far outweigh the risks, but don't say we didn't warn you.
Risks of overclocking
The biggest risk when overclocking is the chance of damaging or destroying the part you were trying to overclock. The damaged part could cause further damage to other components in your system. Both of these can be easily mitigated by being careful to double check that everything is set up right and overclocking in small steps.
Another risk that must be taken into consideration is a shorter life span. Overclocked components take more wear and tear than non overclocked components. Heat is one of the biggest culprits in decreased lifespan.
Other risks include erratic performance, random shutdowns, and data loss. You can read some of the horror stories here
What you can expect
The benefit of overclocking is a faster computer. But another common question asked is how much faster. Again, this is one of the biggest problems with overclocking. There's no way to know how much a part is going to overclock until you test it. Research done before buying a part can increase the chances of getting a highly overclockable part, but there's never any guarantee that a part will perform better than it was sold at.
Understanding the technobabble
Entering the world of overclocking can be intimidating. There's plenty to learn and lots to read, and of course the real risk of damaging your computer. One of the excellent resources of this wiki are definitions of terms that you'll commonly (and not so commonly!) encounter while overclocking. Here are some of the most common terms with brief definitions. Follow the links or search the wiki for more details.
Benchmarking: methodical testing of performance.
BIOS: Basic Input/Output System. A program that configures your computer's hardware at boot time.
Front side bus or FSB: A set of electrical connections which pass signals and data between the major components of your motherboard.
Heatsink: a metal part which increases the surface area of another part in order to help it radiate more heat.
Jumper: a type of switch, used to configure system hardware or peripheral devices.
Memory ratio: A ratio between the speed of the RAM clock and the FSB.
Multiplier: A ratio between the speed of the CPU and the FSB.
Voltage: The amount of energy available to an electrical part.
Where to start
While overclocking your graphics card looks much simpler, it is much more risky. Graphics cards are easier to fry because they don't have a large heatsink to help keep them cool. Most don't have a magic reset button to reset them to their default settings. You should pick a spare computer if you have one, or the computer that is easiest to replace. After you have selected your test subject, you need to find the reset jumper to reset your BIOS in case your computer fails to boot during your overclocking experiments. You should look in the documentation for your motherboard or your computer for the "Reset BIOS" jumper. They exist on almost all motherboards. The jumper will reset your BIOS to the default settings, which may not be the same settings that you are currently using. So next, you want to write down all the settings that are currently set up in the BIOS. While this is a bit long and tedious, this will allow you to get the computer up and running again in case something goes wrong.
With your disaster recovery plans in hand, you are ready to make your first overclock. After doing some research on your CPU you should have an idea how well it should perform. Before you starting overclocking though, make sure to benchmark your system first so you know how much of a difference your overclock makes. Feel free to experiment with your basic settings (FSB speed, CPU multiplier, and RAM ratio) to see what kind of overclock you can achieve. If you would like further help, see Overclocking Tutorial. Good Luck.
The Heat Barrier
You may have noticed in your starting overclocking experiment that you couldn't achieve as good as overclock as some people have achieved. The thing that is likely causing you trouble is heat. The hotter a processor is, the more likely it will fail to operate. The more work your CPU does, the more heat it generates. Thus, if you don't have enough cooling, your processor is likely to fail when you are using it the most. This is the reason most overclockers stress test their computer for hours on end. It ensures that they have enough cooling to keep the processor cool no matter how hard they stress it.
What generates heat
Every component in your system generates heat, though some more than others. Below is a list of the hotter components in your system. This list is roughly ordered from hottest to coolest.
Processor
This is usually the hottest component in your system. Some CPUs can reach over 90 degrees Celsius, close to the boiling point of water. CPUs are usually cooled by a massive heatsink and fan. While CPUs can get really hot, it's recommended that you try and keep them below 60-70 Celsius to prevent stability issues.
Graphics card
Graphics cards are getting hotter and hotter trying to give you the best performance in todays games. High end graphics cards are getting harder and harder to cool. In an effort to tame the hot temperatures of these beasts, graphics card makers have resorted to using dual slot coolers and high speed fans. The down side to these efforts are the increased noise the high speed fans generate.
Hard drives
Hard drives can add a substantial amount of heat to a system. Hard drives are usually the first thing cooled by the fresh air brought into your system due to their position in the front of the case. While keeping them cool is usually not an issue, they can raise the ambient temperature in your system, making it hard to cool the rest of your components.
Chipsets
While usually overlooked, your northbridge and southbridge are also susceptible to heat failure. These little chips are the traffic cops of your computer. As you increase your FSB speed, these chips start to heat up. If they are not properly cooled they can cause your computer to stop functioning. Make sure these little guys have plenty of cooling.
Memory
Last, but not least, the RAM in your system also need to be cooled. Nowadays, heat spreaders usually come default with performance RAM. Make sure you have plenty of airflow and a low ambient temperature to keep your RAM happy.
Advanced cooling
One of the biggest differences between a basic computer and an overclockers computer is the type of cooling it uses. The default cooling in your computer is usually designed to keep the system cooled as cheap as possible. You can often buy aftermarket cooling solutions that will outperform the default one. These cooling setups will allow you to overclock your processor more by removing more heat from your computer. Your computer can be cooled in a variety of different ways.
Air cooling
By far, the most common cooling solution is air cooling. The basic design involves bringing in fresh cool air from the front of your case to cool your components, then expelling the hot air out the back of the case. You can buy larger aftermarket heatsinks to cool your processor better. These heatsinks can greatly expand your overclocking potential.
Water cooling
As you delve deeper into the overclocking community, you will find some people like to use water to cool their computer as opposed to air. Water cooling allows you to pull even more heat away from the hot parts of your computer, but is also difficult to set up. If you are not careful, you can get a leak which can destroy your computer. Make sure to do your research before attempting to use water cooling.
Exotic cooling
There exists even more hardcore than water cooling. Exotic or extreme cooling solutions can often keep a processor's temperature below freezing! Some of these methods are pelter, phase change, and dry ice cooling. These cooling solutions are often expensive and can be even more difficult to setup than water cooling. Do not attempt to use any of these cooling solutions without help.
Designing an Overclocked System
One of the greatest joys and hardest challenge for any overclocker is designing and building a system for overclocking from scratch. When building the system there is several things you have to keep in mind.
Budget and Objective
First and foremost, when building any computer, you have to know your budget. Without knowing how much you can or want to spend you won't be able to make any informed choices on how much to spend on each part. Next thing you need to know is what you are going to be doing on your computer. If you are going to be making a computer mainly for playing games, you will need to dedicate a large section of your budget to your video card. If you know you are going to be editing large video files, you'll want to have fast hard drives and a lot of RAM. Know what you are going to use your computer for and what parts you need to spend money on.
Risk
When you are selecting your parts, remember that no matter how many people got great overclocking results with the same part, there's always a chance that you can end up with a dud. While it's tempting to buy that low end processor that all the overclockers are raving about, remember to never buy a part that you won't be happy with if you can't replace. Last thing you want is to be stuck with a low end part that won't overclock in your high performance system.
Performance premiums
When selecting your parts for overclocking, you will often find yourself spending more money on a part that will overclock than you would otherwise. Sometimes a performance part will only cost you a few dollars more, other times that difference can be in the hundreds. There's often a large range of product performance. Usually it is best to start in the middle and work your way out as needed.
Return on investment
Not only do you have to balance how much you need to spend on each part in your system. You often have to judge if the extra cost for a high performance part or superior cooling system is worth it. To keep this balance you usually look at your return on investment or ROI. To calculate this, you determine how much extra performance you are going to get by purchasing a given part.
For example, you are looking at getting 2 GHz processor that costs $200. If you spend $200 on a cooling system, you can overclock that processor to 3 GHz. In total it cost you $400 to get a 3 GHz processor. Now if the normal 3 GHz processor is only $300, you are better off getting the 3 GHz processor and saving yourself $100 to spend elsewhere.
External links
- A Brief History of Overclocking at arstechnica.com
- Overclocking's Impact on CPU Life at overclockers.com
This article is one of the January 2007 writing contest entries.
