Overclocking Your Core 2 Duo
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Disclaimer: Overclocking can be dangerous. While you should achieve a good overclock by following this guide, I do not take responsibility for any damage that may occur. Overclocking is your choice.
Since this processor is now becoming more than dominant on the market, I thought it only appropriate to share what I’ve gleaned in my long relationsihp with mine. Note that I have not even modified the cooling system. Everything here is done on the standard 2000-3000RPM fans shipped with all modern Intel processors. This series is a very overclockable one, but there are a few considerations to bring up when purchasing one.
Several models of Core 2 Duo use the same chip at reduced clock speeds. If you purchase an e6600 Conroe (what I have) it is the same exact hardware as an e6800 Conroe, and can be overclocked to at least that speed with no effort (with a handful of rare exceptions). The reason beihnd this is the way Intel manufactures their chips.
Intel will make a batch of Conroes, and test how far they can go while remaining stable and at the default voltage. Some of the chips perform extremely well, and can clock to the series’ maximal speeds with stock voltage. Most are slightly unstable at those speeds, and are clocked down a bit to remain stable. The lowest end chips are a totally different type. These middle-range chips are very easily overclocked. In the series covered here, this means the e6600. Buying an e6800 is only advisable if you don’t want to overclock, or if you really feel like spending the extra money for that last bit of speed. Once you have your processor, it’s time to overclock it. To do this you’ll need a bit of background information.
To identify specifics about your processor, and view it’s actual speed (Windows will tell you the default speed usually) you can either look in the boot screens or use a program. The best program for the job is CPU-Z, and it also displays all kinds of information, including RAM timings, CPU multipliers, etc.. It’s truly an invaluable tool for the overclocker.
Overclocking essentially means to squeeze more performance out of the same hardware. It generally refers to the main CPU in the PC, and is much simpler than you may think. You are essentially balancing variables.
- As you increase the speed of your processor (regardless of specific method used to do this), it is going to become less stable.
- In order to restabalize the processor, you increase it’s voltage.
- When you increase the voltage, the processor consequently generates more heat.
If you are familiar with electronics, your processor (aside from it’s processing capabilities) is for all intents and purposes a variable resistor.
There is a maximum temperature that a processor can take before being overwhelmed, and this is called the “tjunction” or “thermal junction”. For Core 2 Duo Conroes this is 85degC (degrees Celsius). A processor of this series is relatively safe anywhere under 70degC, and if you go higher you risk permanent damage. The goal here is to see how high you can get the speed without being higher than 70degC under load. Most people shoot for load temperatures around 55degC, for reference.. Think I’m crazy? Comment about it!
Being “under load” is the proper way of saying that you’re doing something performance-intensive, like a game or a large calculation. In order to test there are many tools available. For dual core processors (like the Core 2 Duo), the tool of choice is “Orthos“. This program will tell you lots of information, and stress the processor heavily on both cores. This essentially simulates the maximum level of activity that you can reach. It also tells you if errors occur in the calculations. This is helpful, because if errors occur, your processor is becoming unstable (and could cause applications to crash, etc., with these computational errors). This is where the opinions of my fellow overclockers and I vary.
The majority of overclockers would say that you should be able to run Orthos indefinitely without overheating, errors, or any other indication of a problem. I disagree! Orthos is more stressful than even games like Crysis (as of now the most intensive) are to the processor. Even if Orthos causes your processor to overheat and/or have errors, it doesn’t mean that it would be a problem for you on a regular basis. I shoot for 30 seconds of stable Orthos time. You can really tell if you’re having instability within the first second you start Orthos on it’s testing - if the CPU is unstable, the PC will generally crash instantaneously. If you can get through a few seconds of Orthos, it’s a pretty stable overclock. If you can leave it on forever, it’s a very stable overclock. I shoot for the middle ground here, and have had no problems with my method. I used to use an overclock of 3.3Ghz on an originally 2.4Ghz e6600. In orthos, the computer would heat up quickly and Orthos would crash (or the PC) in a few seconds. Ignoring this, I tested further and played Oblivion, which (with mods) was still very taxing on my machine. I was able to play for hours with no errors, artifacts, glitches, or unacceptable temperatures. As long as you aren’t pushing the CPU to 100% with incredibly complex calculations, you don’t need a fully Orthos-stable overclock. Back to our discussion of theory..
With voltage comes heat. This is a fact of life, so burn it into your memory. In order to achieve higher and higher overclocks, you can cool your processor better and better to keep it’s temperature safe while still increasing voltage. Keep in mind that the processor also has a maximum voltage recommended by the manufacturer, and in this case it is 1.55v. The underlying principles I’m teaching here apply whether or not you’ve got an amazing cooling system. You’ll simply be able to achieve higher overclocks than those of us on stock cooling. The only thing I haven’t explained now is how to actually do the overclocking, and there are a few ways.
Some motherboards provide software that can communicate directly with the motherboard and do things from within Windows. This may seem very convenient, but there are several problems with this approach:
- Your copy of Windows will overclock the CPU on boot in many cases, meaning that the overclock doesnt apply to things outside of Windows.
- Since it does this when Windows starts, there is no way to disable it without booting into safe mode and toying around with startup options if you get a bad overclock.
Some programs actually interface with the BIOS, meaning that the above two drawbacks aren’t there. However, would you trust Windows with your BIOS? I won’t. There are a few more reasons, but that should be enough for you to decide if it’s for you or not. The advantage is that you can test various settings much more quickly than rebooting between tests, achieving an overclock in a few minutes instead of an hour or so. Worth it? I didn’t think so, but maybe you do.
An example of the JumperFree Configuration screen on an ASUS board’s BIOS.
My preferred method is through the BIOS (Basic Input/Output System, though I’ve heard it stands for a few different things).The BIOS is the first little pieces of code that tell your PC to come to life. It’s settings are stored in the CMOS (Complimentary Metal Oxide Semiconductor), and can be modified by going into “Setup” while your PC is booting. In many cases this is either the “Del” key, or the “F2″ key being pressed at the memory test (or company logo) screen. There will be information on your screen to the effect of “Press XYZ to enter Setup”, where XYZ is the key to press. Once in the BIOS, there are many options. What you will be looking for goes by many names, and I can’t list every way they sort and categorize the BIOS for you. Some common options, however, are:
- JumperFree Configuration (ASUS boards)
- Overclocking (Your board is probably designed for it if the menu is this blatant)
- CPU Configuration
- Many other names.
If you’re having trouble, check any “Advanced” sections. If all else fails, find or download a copy of your motherboard manual and look through it.
Once here, you’ll be presented with a plethora of options that you likely won’t understand all of (if you do, why are you here?). There are a few different ways to overclock, but I use the FSB (Frontside Bus) method. The FSB is the connection between your processor and your North Bridge. If you don’t know what a North Bridge is, don’t worry about it. It isn’t necessary to know every detail. Basically we are going to increase the FSB’s speed, which will increase the rate at which the processor goes as a result (and more of your system, meaning that lots of things will become faster, so be careful). In newer motherboards, the FSB is not a simple number as it once was. You’ll read that your FSB is 1066mhz, for example, and then it will show 266 in the BIOS.
Why? There is a calculation going on that essentially means that the FSB is 4x as fast as the number you set here. 266×4=1066 (roughly). My reason for telling you this is so that you don’t think you can set this number all the way to 1066, as this would be a FSB of more than 4000 (and would quickly kill your system). My FSB is set to 366, which yields an FSB of 1464.
“How does this affect my processor speed?”, you’re probably asking. I was just getting to that. Different models of processors come with a different set of numbers called “CPU multipliers”. On an e6600, you get 6 and 9. The number in your BIOS for the FSB can be multiplied by this number to get the effective CPU speed. I had been shooting for a speed of 3.3Ghz (ambitious, since the stock speed is 2.4Ghz and I’m on stock cooling). The first step was to make sure that all power-saving technologies (in most cases “Intel SpeedStep”) are disabled. These change your multiplier from the higher one (my 9) to the lower one (my 6) when idle. This can cause lag in games, instability, and is generally not a good thing for an overclocker (or gamer, really). This technology is designed to save power in a business or enterprise environment, and really has no place in a performance-oriented PC. With my multiplier locked at 9, I then did some math. If I wanted a 3.3Ghz speed, that was 3300Mhz. 3300/9=366.66 repeating FSB speed. I then changed the number, and increased the voltage a tick or so I believe I ended up at 1.22v). Booting up, I saw no problems. I was able to get some time on Orthos, and everything was running faster. I kept this overclock for some time, but then started to notice frequent bluescreens (operating system failures). This indicated to me that since the errors there made no sense, the overclock must have been too aggressive. I decided to decrease it by 150Mhz, to 3.15Ghz. This led me to some more calculations, 3150Mhz/9=350 FSB. I set that, and have been fine ever since (with little performance drop from the original OC). My temperatures are 55-60degC idle, and 65-70degC under load.
Some people will try to scare you, and say that temperatures like this can “decrease the life of your processor”. They are right, it’s true! However, it doesn’t matter. How long are you planning on keeping your computer, a few years? Until next month when the new CPU is out? A processor lasts for a few decades without overclocking, and the decrease in lifespan is minimal. Instead of a CPU that lasts 12 years, it may last 11, or 10. Unless this is the last computer you buy, this isn’t a big deal.
If you get into Windows smoothly, and then find that opening anything memory-intensive seems to instantly freeze the PC, it is also possible that your RAM timings are the culprit. As you increase CPU speed using my method, it has a relative effect on the RAM. I ran into this problem once, and solved it by setting the RAM timings by “SPD”. This actually slows the RAM from it’s typically comfortable maximum timings, but since the whole system is running faster, the end effect is a more stable overclock, with the RAM running faster than before anyway. It is also possible to change the voltage to your RAM on many boards, and this can help greatly. Make sure you check the documentation on your RAM before doing this, however! I use Corsair Dominator sticks that run at 2.4v maximum, which is high for RAM (and thus good for overclocking).
Overall, overclocking isn’t as complex as you may have thought. There was a lot of information here, but it can be summed up like this:
- Speed leads to instability, which requires more voltage, which produces heat.
- Cooling systems and higher multiplier CPUs allow for bigger overclocks.
- Every CPU has a temperature at which damage can occur, and at which it shuts down, called a tjunction. They also have a maximum recommended voltage (Core 2 Duos have 1.55v).
- Changing the FSB speed affects the CPU speed according to “BIOS FSB x CPU multiplier = CPU speed”.
- The FSB on the box or manual of the motherboard is calculated by “4 x BIOS FSB = FSB”
- Use the boot screens or CPU-Z to view your processor’s actual speed, and other information.
- Use Orthos to test stability, 30 seconds or so should be usable.
- RAM can affect stability when FSB is increased, so tweaking that can help stability.
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