by Doors4ever
08/01/2007 | 06:47 PM
Everyone can feel confused in a strange situation. When you find yourself in an organization for the first time, you don’t know where to go and whom to talk to. When you sit down at the steering wheel for the first time, you can’t make out what to do next with the vehicle. You don’t know what to do when you first turn on your PC or enter the Internet. You’ll get the experience over time and go right to the elevator or turn on the ignition or perform the habitual sequence of actions on your PC almost subconsciously. But you need a guide at first and this role is going to be played by this article.
<%BANNER[article]%>Why do you want to overclock, anyway? I guess there are four types of overclockers.
There are beginner overclockers. The beginner has already got a PC and has no choice of the configuration. He has to deal with what he’s got already.
There are thrifty overclockers. They want to have as much performance as they can yet spend as little money as possible. The PC is assembled out of simple, cheap and outdated hardware parts the person can afford. The default performance of such a PC is below necessary level, but it can be usually overclocked to a more or less acceptable level. A thrifty overclocker is not necessarily a poor person. There are just a lot of other values in our lives besides computers. You may want to invest your money into your education, family or recreation instead of your PC.
Experienced overclockers have somewhat different objectives. Their goal is to get maximum performance and fun without overpaying for that. It’s silly to waste your money purchasing senior (i.e. expensive) components, yet it is also silly to limit your own opportunities by saving on trifles. This overclocker considers numerous factors as he picks up every component. He wants an overclocker-friendly mainboard, a highly overclockable CPU, and a quiet yet efficient cooler. The resulting performance of his PC will be very high, comparable to or better than the default performance of a system assembled out of top-end components. Although such an extremely high performance may not be vitally important, the overclocker finds his pleasure in the feeling of satisfaction from a job well done.
And finally, there are PC enthusiasts whose goal is to get the highest possible performance at any price. They use everything – top models of components and extremely low temperatures – to find themselves on a breathtakingly high peak, unattainable by the crowd. It’s a kind of sport where you can enter the top ten, five or three and that’s the only reward a PC enthusiasts needs.
Of course, these categories are not sharply outlined. There are no definite landmarks between them. Beginners become experienced overclockers over time while experienced overclockers may go in for extreme experiments. You can meet such an exotic combination as a thrifty enthusiast even!
Anyway, you have to begin with something, and I will begin with the first and most important point.
Don’t skip this section! I realize it’s boring and uninteresting to search for and digest information. You just want to know the magic buttons you should press in order to get the necessary result – an overclocked PC. But such universal buttons do not exist! They are different in every situation and you have to have some knowledge in order to find them.
After all, if you don’t want to do any overclocking, you shouldn’t probably be reading this at all. And if you do, you will anyway have to learn everything from your own experience sooner or later, so why now learn it right now? You don’t want to pay for your knowledge with burned-out or damaged components and with wasted time and money when there is information waiting for you to apply it to your purpose.
First of all, you need to know what you will be dealing with. If you have assembled your PC with your own hands or at least taken part in choosing the configuration, you should already know what components it consists of. If you don’t, you should identify each component first. Learn your PC and its parts, browse through your mainboard manual. Run informational programs and a few performance tests and write down the technical characteristics, temperatures and voltages under load and in idle mode. This information is going to be helpful afterwards. Knowing the exact configuration of your system, you can make a precise enough guess at the possible level it can be overclocked to. The performance data will show you how your system performance has increased after overclocking. Sudden fluctuations of the voltages and temperatures are indicative of dangerous situations you can identify and avoid. With these preliminary tests you can also make sure that your system is stable in its normal operating mode.
Every overclocker has a wide range of software tools that fall into a few groups:
There is no sharp separating line between the categories. Informational utilities can often benchmark performance while monitoring tools can overclock as well.
Informational & diagnostic utilities can accurately identify your system configuration. The two most advanced suites are Lavalys Everest and SiSoftware Sandra. Their capabilities are not limited to reporting the configuration, though. These software suites can perform monitoring functions, benchmark performance, and test the system for stability. However, you don’t have to run these voluminous suites, especially as only a part of their functionality is provided for free. There are many less known programs of the same type, e.g. WinAudit or PC Wizard. Instead the universal suites you can use a set of small, free-of-charge special-purpose utilities. For example, overclockers make wide use of the CPU-Z utility that reports information about your CPU as well as mainboard and memory. For more control over the memory timings you can use the MemSet program.
The best of universal monitoring tools have always been developed by enthusiasts, by independent developers. Unfortunately, this is the reason why they are usually short-lived projects. MBProbe was the first abandoned program and then we lost Motherboard Monitor. Today, SpeedFan is the most popular monitoring tool.
The CPU should better be overclocked using BIOS options. If you can’t find them in your mainboard’s BIOS, you can try the universal Windows-based ClockGen program. You can also look up on the CD enclosed with your mainboard for any exclusive program that can overclock from Windows, control the fans, and provide monitoring options.
The range of programs for overclocking graphics cards is broad as well. RivaTuner is perhaps the best in its class, but you may also want to use PowerStrip, NiBiTor, ATI Tray Tools, ATI Tool, etc.
Neither program can give you a 100% guarantee of stable operation of an overclocked CPU but your chances grow up dramatically if you use two or three such utilities. The stability check can be performed with OCCT, S&M, Prime95 or any other program that can load your PC heavily. You can even run your favorite 3D game for that.
As for performance benchmarks, there are hundreds of them that can test the system at large as well as single components. The BenchmarkHQ website offers a long list of useful utilities.
We touch upon overclocking issues in most of our reviews. If you are regularly reading our news and reviews, you should have already accumulated enough knowledge to guide you in your practical experiments. The CPU overclocking statistics can give you an idea of what you can achieve. You can also refer to our forum for discussions of overclocking related problems.
You can also refer to our forum for discussions of overclocking related problems.
You can read one of the latest articles called CPU Overclocking Guide. And you shouldn’t ignore an article if it doesn’t mention your specific CPU model. There are universal overclocking basics and if you’ve got a clear understanding of how to overclock a Pentium III, you will easily overclock any modern CPU.
If you are a beginner overclocker and you’ve already got a PC, it’s both good and bad. It’s bad because you can’t change anything while even one weak component, e.g. a low-wattage power supply, can be an insurmountable obstacle to overclocking the whole system. It’s good because you don’t have to face the problem of choice.
This is one of the most difficult decisions you have to make when putting together your overclocking-ready system. There are thousands of factors to be taken into account like the range of currently available components, the comparative worth of different models, the pricing, the ease of assembly, upgrade opportunities, and even the exterior design. It is rather simple and easy to overclock a PC, but it’s very hard to pick up an optimal combination of hardware parts.
Fortunately, discussing this goes beyond the subject of this article. I’ll only touch upon it again when the choice of parts will determine the choice of an overclocking method.
Overclocking means clocking a hardware part at a frequency higher than the default one. You don’t have to know why overclocking is possible at all. It may be due to a high margin of safety provided by the manufacturer, due to marketing reasons that made the manufacturer set lower default characteristics than possible, or due to the use of faster components than necessary. Whatever the reason, your task is to make good use of the offered opportunity.
In a PC, everything is standardized and synchronized. The standardization is obligatory for components from different makers to be able to work together at all. The synchronization ensures that the components work together smoothly. The frequency of the system bus (or Front Side Bus – FSB) is considered the basic frequency of the system. The rest of the buses the various devices and components are connected with usually work at lower frequencies that are generated from the FSB frequency by means of divisors. The CPU frequency is currently much higher than the FSB frequency and is generated by means of a multiplier.
For example, the Intel Core 2 Duo E6300 processor works at a bus frequency of 266MHz. Its frequency multiplier is x7 and the multiplication of the two yields the resulting CPU frequency, which is 266x7=1.86GHz. It means that the CPU frequency can be increased by increasing the FSB frequency or the multiplier.
Senior models of modern CPUs have an unlocked frequency multiplier and permit to increase it, but such CPUs are too expensive in comparison with junior models from the same family. It is not reasonable to buy one because overclocking can lift the performance of the junior models up to the level of the senior ones and even higher.
Thus, CPU overclocking usually boils down to increasing the FSB frequency. Taking the same Intel Core 2 Duo E6300 as an example, if you increase its FSB frequency from the default 266MHz to 400MHz, the CPU frequency will grow up to 2.8MHz, by 1000MHz almost. If the FSB frequency is increased to 500MHz, the CPU will be clocked at 3.5GHz, etc. This is in fact all the information you need to go into your mainboard’s BIOS Setup, increase the FSB frequency and overclock your CPU, but there are some things you should be aware of yet. You’ll learn more of them eventually, and some of them are unknown even to me because new CPU models have peculiarities of their own. But again, there are basic things you can rely upon in all your overclocking attempts.
Before you begin to overclock your CPU, you should do some preparatory work. Check for BIOS updates on your mainboard manufacturer’s website and read through the list of changes. There have been numerous occasions when a mainboard with poor overclockability would transform miraculously after a BIOS update. New BIOS versions not only correct errors, but sometimes add new parameters or expand the range of the available ones. You can read the version number of your current BIOS during the startup. If the information disappears too quickly, press the Pause key on your keyboard. Sometimes the version number is shown in BIOS Setup. You can also learn it from informational utilities or special-purpose BIOS updaters. You don’t have to write every BIOS version, from the oldest to the newest, into your mainboard. The freshest version includes everything from the earlier ones. And even if the latest version is not the most optimal for overclocking, it is at least sure to be free from the errors of the earlier versions.
So, you are in your mainboard’s BIOS and want to know what to do next? Perhaps you’ve got an “intelligent” mainboard that can do everything by itself, and you only have to specify the desired level of CPU overclocking or the FSB frequency. However, it’s better to take care of everything by yourself to avoid any problems. This will save your time and components and will ensure the best possible result.
You should reduce the memory frequency first. As I said above, everything is interrelated in the PC, so when you are overclocking and increasing the FSB frequency, the memory frequency increases proportionally. And if the memory works at a high frequency by default, it may become the limit to further CPU overclocking. It’s desirable to set the minimum possible memory frequency in the BIOS. Don’t worry about the performance reduction. You’ll increase it back through overclocking. Moreover, you can return to the memory after you’ve found the maximum frequency of your CPU and try to increase it speed back again.
Next you should set higher memory timings, at least the basic ones, for example 5-5-5-15-2T for the widespread DDR2 memory type. You should do this for the same reason as you reduced the memory frequency, i.e. to prevent the memory chips from interfering with the CPU overclocking. Memory can work at a high frequency with high timings or at a low frequency with low timings. Sometimes two or more combinations of possible settings are written into the memory module’s SPD chip. The reduction of frequency can be taken as a permission to reduce the timings if the latter are set up by the mainboard automatically. This combination of a low frequency and low timings may be quite normal for the default operating mode of the CPU, but low timings may become a problem when the memory frequency has increased due to your overclocking attempts.
If BIOS parameters are set at Auto, the mainboard can control them automatically. Mainboards control their parameters normally most of the time, but not always. That’s why you should avoid this and specify parameter values explicitly.
For example, you may want to fix the CPU multiplier at its default value. I know of cases when an intelligent mainboard’s BIOS reduced the multiplier at startup. Perhaps it was an error, but anyway.
Moreover, you may also want to explicitly specify the voltages so that the mainboard didn’t increase them at overclocking. The memory voltage should, on the contrary, be increased a little to make the memory chips stable. By the way, it’s sometimes not easy to learn the default voltage values. Many mainboards show the CPU voltage in a special information line. Sometimes the default voltage is the minimum possible one. The CPU voltage can also be read with a special program like CoreTemp or RM Clock.
You can also try to determine the voltage by a guess method. The mainboard normally selects the default CPU voltage, and you should view it with some monitoring utility or in the PC Health section of the BIOS. Then specify a voltage value explicitly, trying to guess it so that it coincided with the value measured when it was set automatically.
The Spread Spectrum feature should be disabled unless the mainboard disables it automatically when overclocking. This option is meant to minimize electromagnetic interference the operating computer generates but it may limit your system’s overclockability.
Some mainboards are able to overclock the graphics card in automatic mode. If the graphics card is under heavy load, its frequencies are increased a little. You should disable this feature. You can’t get a big performance increase this way, but problems are quite possible.
Now you know enough to try to overclock your CPU. The step-by-step instructions are simple: increase the FSB frequency in the BIOS, save the settings, boot up the OS and test your PC for stability while keeping your eye on the temperature reading. If you haven’t ever seen a BIOS screen in all your life and can’t find the necessary settings, browse our CPU Overclocking Guide. The frequency can at first be increased with a big enough step like 50MHz or even 100MHz, depending on your CPU model. You should have learned the frequency peak of your CPU and set the frequency accordingly, but the potential of a given sample may differ greatly from the average value. Then, reduce the step to 20, 10 or even 5MHz. Overclocking with a 1MHz precision only makes sense when you are trying to set a new record. For everyday operation, it’s better to have a reserve of stability to safeguard yourself against the natural fluctuation of such characteristic as temperature and voltage.
You go on increasing the frequency while the system is stable and passes all the tests. When errors occur, you reduce the frequency and thus find the limit for your particular CPU.
Can you overclock more? Yes, but you have to increase the voltages for that.
It’s hard to give a short answer to this question. You should first decide what voltage needs increasing. This is verified through experimenting. Try to increase the CPU voltage by one or two minimum steps in the BIOS and then check out if the CPU can now work at a higher frequency than before the voltage increase. If it can, begin to search for the frequency limit under the new conditions. If it cannot, you’ve increased the wrong voltage.
Besides the core voltage, the mainboard itself can limit further overclocking if you have set a high FSB frequency. Try to increase the voltage on the chipset’s North Bridge a little. Try to change voltages in combination, e.g. increase the FSB termination voltage if your BIOS offers this option. You have fixed all the voltages at their defaults before overclocking, but now you can get a hint from your mainboard: set the voltages to Auto and see what ranges they are changing in.
How high can you increase the voltages? There are three factors that can stop you: the mainboard’s capabilities, a too high temperature, and a lack of purpose. If your system reacts eagerly to a voltage increase and the temperatures remain within normal ranges, why not continue? But if you need to increase your CPU voltage by 0.3V to overclock by 100MHz, I don’t think it makes much sense. The effect from such a small frequency increase won’t be conspicuous for a modern CPU but your system will be put under a stress and the temperature will grow up, too. The CPU temperature increases along with its frequency, but it does so at a much faster rate when you increase the core voltage.
A CPU temperature of 40-50°C is normal. It can grow up to 60°C under load but you should avoid a temperature of 70°C and higher. Replacing the cooler is not the only option to decrease the temperature. If your PC is rather old, you may try to reinstall the cooler and update the thermal grease and the temperature should go down considerably. The temperature will be growing up inevitably in a small and poorly ventilated system case. Installing system fans should help.
Talking about temperatures I mean the CPU temperature in the first place, yet it is not the only one that you should keep your eye on. Keep track of the chipset temperature, especially if you have increased its voltage. The thermal sensor is built into the North Bridge in Intel’s new chipsets. So far there is no program that can monitor this temperature, but such software will surely come out soon.
Mainboards can regularly monitor two temperatures, CPU and system. The system temperature is not the chipset temperature. There is a thermal sensor on the mainboard, usually located near the I/O chip (from Fintek, ITE or Winbond), and its reading is shown as the system temp. Depending on the exact location of the sensor, this temperature may be an important indicator or may be quite useless (and even not changing at all).
Note also the temperature of the MOSFETs near the CPU, especially if you use a liquid cooling system. These usually become very hot under load, but few makers of liquid cooling solutions provide any means to cool them. Memory modules remain almost cold even after a considerably voltage increase but become hot when the memory chips are being accessed intensively.
There is yet another way to increase your system performance. Almost all of modern CPUs allow decreasing the frequency multiplier. You can decrease it and increase the FSB frequency appropriately, keeping the resulting CPU clock rate unchanged. The FSB frequency affects the overall system performance. The higher it is, the faster data flows throughout the PC. Thus, a 3GHz CPU working at a 300MHz FSB with a x10 multiplier will generally be faster than the same 3GHz CPU working at a 200MHz FSB with a x15 multiplier.
This safe and free method of lifting the performance of your system a little more won’t suit everyone, however. The fact is, the power-saving technologies implemented in CPUs stop to work when you change the multiplier because they are themselves based on the reduction of the multiplier and voltage in idle mode. Such technologies play an important role in reducing power consumption and temperature, so this method will only suit people whose PC is loaded all the time, e.g. with distributed computing software. It’s going to be indeed free for them as they get an increase of speed without losing in anything.
CPUs with the Core micro-architecture are the most appealing nowadays. They overclock well, so I’ll pay them most of my attention here.
An annoying thing you have to keep in your mind as you are overclocking a Core processor is the so-called FSB Wall. This term refers to the maximum bus frequency this sample of the CPU can work at. Thus, it is convenient to begin to overclock a Core processor with finding its FSB wall. To do this, reduce the multiplier to the minimum of x6 and see what FSB frequency your CPU can be overclocked to. Your CPU may be not stable at this frequency with the default multiplier, but at least you get a notion of what your CPU can potentially do.
For example, CPUs with a default bus frequency of 200MHz can be but seldom overclocked to over a 400MHz FSB. You should take this fact into account when you are choosing your CPU. There is no sense in overpaying for a senior and more expensive model if you can take a junior one and overclock it but note that the top frequency of a junior CPU with a default multiplier of x8 is likely to be limited by the FSB wall at 3.2GHz or something. Most likely, you will stop at 3.0-3.1GHz, which is low. You don’t want such limitations, do you? So, you may want to consider a CPU with an x9 multiplier instead.
As for CPUs with a default FSB frequency of 266 or 333MHz, people often buy a junior model with a multiplier of x7, but such CPUs may be limited not only by the FSB wall but also by the capabilities of your mainboard and memory. It is better to use CPUs with an x8 or higher multiplier, yet you have to face a new problem with them, the FSB Strap.
The FSB Strap is not a feature of the CPU, but of the mainboard and chipset. It is the frequency the chipset switches into another operation mode at, increasing the latencies and bringing about a performance hit. Gigabyte mainboards on the Intel P965 Express chipset slow down as soon as you try to overclock the CPU. ASUS mainboards on the same chipset deliver excellent performance up to a 400MHz FSB and then use the FSB strap. When testing an ASUS Striker Extreme mainboard on an Nvidia nForce 680i SLI chipset we found a performance hit on transitioning from a FSB frequency of 420MHz to 425MHz (for details see our article called ASUS Striker Extreme Mainboard Review). Mainboards on the Intel P35 Express chipset seem to be free from this drawback, judging by first tests (for details see our article called Asus P5K Deluxe Mainboard: Second Encounter).
Some non-overclocker-friendly mainboards on Intel’s 945 and 965 series chipsets do not support the FSB strap at all (se our Biostar TForce P965 Mainboard Review) and CPUs with a default 200MHz FSB can usually be overclocked on them to a 300MHz FSB or something. This can be corrected with a CPU modification called BSEL mod. By isolating and connecting contact pads on the CPU’s “belly”, the mainboard is made to think that the default FSB frequency of the CPU is 266MHz rather than 200MHz and behave appropriately at overclocking.
So, you should be aware of the FSB strap thing beforehand and try to avoid non-overclocker mainboards. You should pick up your mainboard considering the default multiplier of your CPU so that you didn’t hit the frequency range with reduced performance. Perhaps you will even have to lower the maximum FSB frequency a little to avoid this range. On the other hand, you shouldn’t have much fear of this thing. If your CPU can overclock far beyond 500MHz FSB, you shouldn’t care about the frequency of the FSP strap because the high frequency of the CPU will make up for any performance hits.
AMD processors can be overclocked like any other CPUs but you should reduce the frequency of the HyperTransport bus that connects the CPU with the chipset. It’s usually enough to set an x3 multiplier or a frequency of 600MHz, which is in fact the same thing.
Besides, with AMD processors the memory controller is integrated into the CPU. It means the resulting speed of the system doesn’t depend much on the employed chipset and will generally be the same in most cases. It means you can take almost any mainboard, except for those models that suit poorly for overclocking due to their limited BIOS options, sloppy PCB design, or other such reasons. Read a review of your mainboard to learn if the mainboard you’ve chosen is good for overclocking.
There is another difference from Intel’s CPUs and it is due to the integrated memory controller, too. The memory timings play a more important role for AMD processors, especially with DDR SDRAM. You should test your system in different modes to see if it’s better to reduce the timings rather than to increase the memory frequency.
Note also that AMD Athlon 64 X2 processors on the 65nm Brisbane core are slower than their 90nm Windsor precursors due to slower cache memory and fractional multipliers (see our article called AMD Athlon 64 X2 4800+ Anew: AMD Masters 65nm Technology). The memory frequency on the AMD platform is based on the CPU frequency and integer divisors and the real memory frequency may sometimes be much lower than set in the BIOS, leading to a performance hit. That’s why dual-core processors on the Windsor core are preferable for overclocking. Their overclockability isn’t inferior to that of their technologically advanced but slower mates.
If you think you can sleep well now that you’ve overclocked your CPU, you are mistaken. High CPU frequency is just a means to get a higher performance from your whole system and you have to do more to reach that goal. The CPU means a lot, but the memory timings almost always affect performance whereas performance in games is often determined by the graphics card.
You decreased the memory frequency when you were preparing to overclock the CPU. Now you should raise it back if possible. The general rule is the higher the frequency, the higher the memory performance is. So, you should leave the memory timings unchanged (you have lifted them up previously) but try to achieve the maximum possible memory frequency. It usually helps to increase the voltage, but not too high. It is undesirable to increase the voltage of DDR2 memory higher than 2.1-2.3V. Found the maximum frequency? Good. Now you should find the minimum possible timings for it. As opposed to the frequency, it’s better to have lower timings.
I give you general recommendations, so don’t be afraid to check them out in practice. You may find yourself forced to select an inconvenient divisor or increase the timings too much to get a high memory frequency. Perhaps it will be better, for the overall system performance, to reduce the memory frequency a little, but set lower timings. Run a few tests for different frequency/timings combinations and choose the best one.
Performance in games is largely determined by your graphics card. If you are a dedicated gamer, don’t forget to overclock your graphics card as well. Overclocking graphics cards is an extensive subject that calls for a separate article. It’s not enough anymore to increase the GPU and graphics memory frequencies to get the maximum possible performance. Today, you have to account for the graphics core having multiple subunits clocked at different frequencies. You have to watch for image freezes. You should reflash the graphics card’s BIOS to correct the timings and frequencies.
Now that your system is overclocked and, hopefully, delivers considerably higher performance, you can sleep well. I mean if you can suppress the desire to tell everyone of your success and check out the increased performance of your PC in real-life applications.
Good overclocking luck to you!