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Section 1: Preparing Your Computer

Before you begin overclocking, there are some programs you will need to download. As you overclock your computer, you’re going to need to view important information, such as the total speed of the CPU, the voltage being given to the CPU, the memory timings, etc. To see this information, you’ll need a program called CPU-Z.

The two most informative tabs that you’ll view in CPU-Z are the “CPU†and the “Memory†tabs. The important information on the CPU tab include: the CPU speed (“Core Speedâ€), CPU Multiplier (“Multiplierâ€), Reference Clock (“Bus Speedâ€), HT Link Speed (“HT Linkâ€), and CPU Voltage (“Core Voltageâ€). If these terms don’t make sense right now don’t worry, they’ll be explained in the following chapter. This information will change during the process of overclocking.

The CPU tab also gives you other information about your CPU, including the CPU model, the stepping, and size of cache in the CPU. These details don’t change with overclocking so we’re not too concerned with those in this guide.

The Memory tab tells you the six most important timings (tCL-tRCD-tRP-tRAS-tRC-CR), the CPU --> Memory divider, and the speed of your memory (“DRAM Frequencyâ€). Remember that DDR2 memory is double data rate, so a reported speed of 400MHz is the equivalent to DDR2 800, or 800MHz effective (EDIT: All DDR, that is, all types of RAM run on AMD systems currently are double data rate; the mathematics remain the same no matter what type -- DDR, DDR2, or DDR3 -- of RAM is involved. -- txtmstrjoe). If your memory is set to DDR2 800 but CPU-Z is reporting a frequency less than 400MHz, it’s because you’re running an odd CPU Multiplier which underclocks your memory. I discuss this topic in the AMD Memory section of this forum, and you can view it by clicking here.

In addition to CPU-Z, you’re going to need various other programs to stress your hardware. Stressing hardware is done to make sure everything is stable. Just because your overclocked computer loads Windows doesn’t mean it’s stable. Stress tests will force your CPU and/or memory to work at 100% utilization for hours. If the hardware can run a grueling stress test for 24 hours, then chances are it can run your video games and other applications without any errors.

One of the best stress tests for dual core CPU’s is a program called Orthos. Orthos is specially designed to stress both cores of the CPU, unlike older programs such as Prime95 which only stresses one core at a time (EDIT: The newest version of Prime now allows up to 4 cores to be stressed). Orthos should be run everytime you change settings in your BIOS to check for stability. This is explained in detail later in this guide. Orthos has several tests you can run, Small FFT, Large FFT, and Blend. Small FFT mainly stresses your CPU, while Large FFT stresses the memory. Obviously, blend stresses both components. To use Orthos, just load the program, choose the test you want from the drop-down menu, and click the start button. If there is an error, Orthos will stop running and make a beeping sound. This means your computer is unstable.

Simply speaking, CPU-Z and Orthos are the only two programs that you’ll absolutely need to overclock well, but several others can be helpful too.

3DMark06 is a benchmarking program that gives you a score that roughly correlates to how well your system will perform in modern 3D video games, with higher scores being better. Your 3DMark06 score is heavily dependent on your video card, but overclocking your CPU and memory can still give your 3DMark06 score a significant boost, especially if your CPU was bottlenecking the capability of your video card (i.e. an X2 4000+ paired with an 8800GT). Run 3DMark06 before overclocking your CPU, and again after the overclocking is complete. It’s rewarding to see how much your 3DMark06 score improves.

Memtest86+ is a utility that stresses your memory. Download the .iso.zip provided by mega_option101 in the link I just posted. Use a program such as Nero to create a bootable CD-ROM. Once the disk has been burned, you can run Memtest86+ by leaving the disk in your CD/DVD drive and restarting Windows. Assuming you have your boot sequence set properly to boot from CD-ROM first, then your computer will automatically run Memtest86+ before loading Windows. If your memory passes tests 1-8, your memory is most likely stable.

Everest is a utility that will determine the latency of your memory. This is very useful when trying to decide between running your memory at xyzMHz and 4-4-4-12 timings or abcMHz and 5-5-5-15 timings.

There are many other programs that some people use (such as SiSoft Sandra and Prime), however the ones I mentioned above are the most popular/useful. Make sure you at least have CPU-Z and Orthos installed on your computer before you proceed to the next section.

Once again, here are the programs I recommend using:
CPU-Z
Orthos
3DMark06
Memtest86+
Everest

In addition to preparing your computer, you need to find out one very important piece of information before you get started, which is the recommended voltage for your memory. DDR2 memory runs at 1.8v by default, but many of the high end memory manufacturers created memory sticks that are meant to run at 2.1-2.3v. If your memory is meant to run at 1.8v, setting it to 2.2v could destroy the chips in a short amount of time. However, if your memory is meant to run at 2.2v, and you set it to 1.8v, it won’t overclock very well (might not even boot at tight timings and 1.8v). So research your memory and find out what voltage it should run at. If you recently bought your memory, check the “specifications†page on the web site you bought it from. For example, if you recently bought a 2x1GB set of Crucial Ballistix DDR2 800 4-4-4-12 off newegg.com, then you could view the web page for the memory, check the specifications tab, and see that it’s listed as 2.2v for the voltage. However, if you bought a 2x1GB set of G.Skill DDR2 800 5-5-5-15 off newegg.com, then you could view the web page for the memory, check the specifications tab and see that it’s listed as 1.8-2.0v for the voltage. This is a very important step, do not skip it.
White Whale
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post #3 of 14
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Section 2: Explanation of the Basic Settings

The first thing you want to do is explore the menus and settings in your BIOS. There are several very important settings that you want to find and familiarize yourself with, and many other settings that you won’t change or need to know much (if anything) about. Let’s go over the settings that you’ll likely have to manipulate while overclocking.

Reference Clock
This is the setting that starts at 200 and is increased to overclock your computer. This is the single most important setting, as the CPU, HT Link and memory all reference this number when calculating their speed. The reference clock is often incorrectly referred to as the FSB, which is an Intel term that has no bearing on AMD 64 X2 systems. The reference clock is also referred to as the HT, HTT, CPU speed, and many other terms that aren’t really correct, however many people and motherboards use them. It is important to note that unlike Intel’s FSB, no data is actually transferred on the reference clock. It is merely a number created by the clock generator that other devices reference to calculate their speed. Your motherboard should give you the option to increase the reference clock by any whole number, up to a certain max value such as 400 (i.e. Auto, 200, 201, 202, 203, …, 398, 399, 400). It is usually a bad idea to increase the reference clock by any more than 10MHz at a time, as large changes can cause your system to fail to post.

CPU Multiplier
This setting decides what number will be multiplied with the reference clock to determine the total speed of the CPU. The setting usually starts at 5x, and can go as high as 16x (some even higher). Some motherboards will only allow whole number multipliers (i.e. Auto, 5x, 6x, 7x, …, 14x, 15x, 16x) whereas others allow half multipliers as well (i.e. 5x, 5.5x, 6x, …, 15x, 15.5x, 16x). As an example, say the CPU multiplier is set to 10x, and the reference clock is overclocked to 215. Your computer will determine the CPU speed as 215 x 10 = 2150MHz. If you increased the CPU multiplier to 11x, the CPU speed would be 215 x 11 = 2365MHz.

HT Multiplier
This setting helps determine the speed of the HT Link, which controls the speed of input/output devices on the motherboard. Most motherboards have a whole number multiplier ranging from 1 to 5 (i.e. Auto, 1x, 2x, 3x, 4x, 5x). The HT Link is determined by multiplying the reference clock with the HT multiplier. Most AM2 motherboards run at 1000MHz by default, meaning that a system that has not been overclocked yet has a reference clock of 200 and an HT Multiplier of Auto (which automatically sets it to 5x), giving 200 x 5 = 1000MHz. As you increase the reference clock to overclock your system, the HT Link will rise to values exceeding 1000MHz. At some point, the HT Link will reach a value that is so high that your system will either become unstable, fail to load Windows, or fail to post. You can bring it back down to a reasonable value by lowering the HT multiplier to 4x or lower. Many AM2 motherboards can run at very high HT Link speeds, such as 1200-1400MHz. However, there is no advantage to running the HT Link at anything above 800MHz, so don’t be afraid to lower the HT Multiplier to regain stability. Overclocking the HT Link past 1000MHz won’t improve system performance. Some motherboards will list this setting as (Auto, 200, 400, 600, 800, 1000). Note that these correspond to the 1x, 2x, 3x, 4x, and 5x multipliers respectively.

CPU Voltage
Also called vCore among other names. This setting controls the voltage given to your CPU. Depending on the motherboard, this setting can have a wide range of values. Most AM2 CPU’s have a stock CPU voltage of 1.30v, and can be safely increased to 1.45-1.50v assuming that you have an aftermarket CPU cooler keeping your temperatures low. When testing for the maximum CPU Speed (this process is described later) you can add stability to the system by increasing the CPU voltage by 0.0125v or 0.0250v increments. Just remember that more CPU voltage causes more heat, so keep an eye on temperatures and invest in an aftermarket CPU cooler for $20-45.

Motherboard Voltage
Also called vChip among other names. This controls the voltage provided to the motherboard’s chipset. Increasing the motherboard voltage can add stability at very high reference clock and HT Link settings. Higher end motherboards might break this down into northbridge and southbridge voltages.

Memory Setting
This setting is one of the two major factors in determining the CPU --> Memory divider, and therefore a major factor in determining the speed of your memory. It will have options that look something like this (Auto, DDR2 400, DDR2 533, DDR2 667, DDR2 800). Some newer motherboards might also allow DDR2 1066. The other factor that determines the CPU --> Memory divider is the CPU multiplier. Calculating the divider and DDR2 memory speeds can be a little complex for socket AM2, so a few months ago I wrote up an explanation that you can read about here: DDR2 Memory Speeds Explained.

Memory Voltage
Also called vDIMM among other names. This setting controls the voltage given to your memory. Every brand of memory has an internal circuit (or IC for short). Some popular memory IC’s are Micron D9’s and Promos. It is the memory’s IC, not the brand of memory, that determines how much voltage the memory can take. Read more about memory IC’s on Enterprise’s well written thread. Some IC’s like 1.8-2.0 volts. Others, such as Micron D9’s, like 2.1-2.3 volts. The same brand of memory might have used one IC in early versions, and a different IC in later versions. So make sure you know what IC your memory has and what voltage it can handle. Google search, check the Specifications on the web site you bought them from (if you just bought them recently), or ask someone here on OCN. Increasing the voltage to your memory can provide stability, but it’s usually not a good idea to give them more than 0.1 volts beyond what they’re rated for, and definitely no more than 0.2 volts. And as always, more voltage, more heat.

Memory Timings
These are often located in the same menu as the memory setting. There are many memory timings, but some motherboards only allow access to the most important memory timings, which is usually not a big deal. Unless you really know what you’re doing, there’s only a few memory timings you’ll need to adjust, the rest you’ll leave on Auto. Let’s take a look at how memory timings are traditionally reported:

4-4-4-12which corresponds to:
CAS Latency – tRCD – tRP – tRAS

You’ll definitely have to manipulate these timings, so make sure you find them in your motherboard. CAS Latency is often called other names, such as tCL. Another important timing that you should find is tRFC (there should be a tRFC for each memory slot, and are usually labeled tRFC0, tRFC1, tRFC2, tRFC3). You want to make sure that all tRFC values are set to the same number, such as 105ns. You’ll also need to change the tRC so locate that setting as well. Finally, you’ll need to find the command rate and make sure it is set to 2T.

Because the tRC and command rate are important settings, you’ll often see me write my timings like this:

4-4-4-12-23-2T which corresponds to:
CAS Latency – tRCD – tRP – tRAS – tRC – command rate

Cool’n’Quiet
This feature is an overclocker’s enemy. If enabled, it will underclock your CPU when your computer is idle. Make sure you find this setting and set it to disabled.

PCIe Clock
This feature controls the frequency of the PCI express slots. Lock it at 100MHz to make sure it doesn’t interfere with your overclock stability. Some motherboards might not even offer this feature, so don’t worry if you can’t find it.
White Whale
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post #4 of 14
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Section 3: Overclocking Theory

Once you’ve browsed your BIOS and familiarized yourself with the settings I described in the previous section, you’re ready to start overclocking. The parts in your computer will be stressed as they’re overclocked, and this added stress will eventually cause them to become unstable. How will you know when your computer is unstable? As you overclock you’ll be running stress tests with Orthos, and if your computer fails the stress test you’ll know it’s unstable. If you made a big change in the BIOS, your computer might even fail to load Windows, or worse – fail to post (failing to post means your computer won’t even load the BIOS). These are obvious signs that your computer is unstable at the current settings. So when your computer becomes unstable, which settings do you change to regain stability? You’re going to have a hard time figuring that out unless you know which part is causing the instability (the CPU, motherboard, or RAM).

Let’s use an example. You have an AMD X2 5600+ that is 2.8GHz at stock speeds. You’re using PC2 6400 RAM that is rated to run at 4-4-4-12-23-2T timings at DDR2 800 speeds and 2.1v. Your settings are as follows:

Reference Clock: 225
CPU Multiplier: 14x
HT Multiplier: 5x
CPU Voltage: 1.35v
Motherboard Voltage: 1.30v
Memory Setting: DDR2 800
Memory Timings: 4-4-4-12-23-2T
Memory Voltage: 2.1v

This means your CPU is overclocked to 3150MHz (225 x 14), your memory is overclocked to 450MHz (900 effective), and the HT Link of the motherboard is overclocked to 1125MHz (225 x 5). You run Orthos for a few hours and no errors are reported, thus you are stable at these settings. Now you increase the reference clock by another 5MHz, making it 230. Your computer posts and loads Windows, but 90 seconds into the Orthos blend test an error is reported and the stress test is halted. Your computer is now unstable.

So how do you regain stability? You need to adjust one or more of the above settings, but which one(s)? Do you add more voltage to the CPU? Do you loosen the memory timings? Maybe the HT multiplier needs to be dropped. You have no idea do you, and frankly neither do I. This is because we have no idea which part is causing the instability. It could be the CPU, memory, or motherboard. We have no idea because we broke a golden rule of overclocking, we did not isolate each part. Instead, we overclocked all three parts (CPU, memory and motherboard) at the same time. Since all parts are overclocked beyond their known stable settings, we cannot determine which part is causing the instability.

This brings us to the point of the discussion: you must isolate each part, finding its limits while keeping all other parts at or below their default speeds. The following three sections will walk you through how to do this. We start with the motherboard, move on to the CPU, then bring in the memory. It is a time consuming process when done properly, but it is by far the most effective method of overclocking.
White Whale
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post #5 of 14
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Section 4: Isolating the Motherboard

The first part we’re going to isolate is the motherboard. Every motherboard is limited in two ways:

First, there’s only so much you can push the reference clock. By default, it is set to 200MHz and runs just fine at this speed. But as you increase the reference clock, you’ll eventually hit some number that causes instability. This reference clock value will be considered the maximum reference clock that your motherboard can handle. Giving the motherboard more voltage might allow you to push the reference clock a little further, but probably not by much. Expensive motherboards can hit very high reference clocks, in the 330-400MHz range. Cheap motherboards might not be able to take as much, and might max out around 220-260MHz (though I’ve seen many cheap motherboards hit well over 300MHz). No matter what motherboard you own, make no assumptions. Follow the process outlined below and find the max reference clock of your motherboard!

The second limiting factor of a motherboard is the HT Link. The HT Link is 1000MHz by default on most AM2 motherboards, and is calculated by multiplying the reference clock by the HT Multiplier. At default settings, you get 200 x 5 = 1000MHz. As the reference clock is increased, the HT Link is overclocked. If the HT Link reaches a high enough value, your motherboard will become unstable. This value varies significantly for every motherboard. Many AM2 motherboards run just fine at high HT Link values (i.e. 1200-1400MHz) and others will hit instability at values as low as 1060MHz. When you hit instability in the HT Link, you have to drop the HT Multiplier by 1x (so 5x becomes 4x, or if it’s already set to 4x then 4x becomes 3x). This will regain stability in the HT Link and allow you to continue to increase the reference clock, pushing your CPU and memory to even faster speeds.

Most people agree that there is no advantage in overclocking the HT Link, it’s merely a side effect of overclocking the CPU and memory. So don’t be upset if you have to drop the HT Multiplier sooner than expected, resulting in an HT Link below 1000MHz, as this won’t impact performance. As long as the HT Link is above 750MHz, you should be just fine.

So our goal is to slowly increase the reference clock until we find the max reference clock of the motherboard. And along the way, we’re going to occasionally encounter instability in the HT Link, requiring us to drop the HT Multiplier. You want to take note of the reference clock values that required a drop in the HT Multiplier. Write down these values so you remember which reference clock values required a drop in the HT Multiplier.

But remember what we discussed in the previous chapter, we need to isolate the motherboard. That way when we hit instability, we know it’s the motherboard and not the CPU or memory. So how do we isolate the motherboard? Simple, we significantly underclock the CPU and memory. Since we’re pushing the reference clock to its limits, we’ll need to drop the CPU multiplier to its lowest setting to make sure the total CPU speed never goes beyond its default speed. Similarly, we’re going to lower the memory setting to increase the CPU --> memory divider, ensuring that the memory never reaches speeds in excess of its default speed. We’re also going to loosen the timings.

Ok, time to get started! Set your computer to the following values (i.e. take them off Auto and manually set them to the following):

Reference Clock: 200
CPU Multiplier: 5x
HT Multiplier: 5x
CPU Voltage: 1.35v
Memory Setting: DDR2 400
Memory Timings: 5-5-5-18-26-2T (keep all other timings on Auto)
Memory Voltage: Whatever the default voltage is for your memory, you should have already researched and figured this out before attempting to overclock.
Motherboard Voltage: Whatever the default voltage is for your motherboard, you should have already researched and figured this out before attempting to overclock.

Save the settings, restart the computer, and run CPU-Z to verify that the settings took effect (CPU speed should be 1000MHz, HT Link should be 1000MHz, memory should be 200MHz, timings should be loosened, etc). You’re now ready to overclock! Do the following:

1) Increase the reference clock by 3-5MHz, go to step 2.
2) Once the computer restarts with the new settings, run an Orthos Blend Test for 2 minutes. If Orthos ran for 2 minutes with no errors, return to step 1. If Orthos failed before the 2 minutes was up, go on to step 3.
3) Drop the HT multiplier by 1x, go to step 4.
4) Once the computer restarts with the new settings, run an Orthos Blend Test for 2 minutes. If Orthos ran for 2 minutes with no errors, return to step 1 and write down the reference clock value that required a drop in the HT Multiplier. If Orthos failed before the 2 minutes was up, then the problem wasn’t the HT Link, and you’ve probably reached the maximum reference clock that your motherboard can handle. You can try bumping up the motherboard voltage to regain stability, but this will probably only allow for a few extra MHz.

After completing this process, you should now know the max reference clock of the motherboard and the values that required a drop in the HT Multiplier. Your notes should look something like this:

A reference clock of 240 required a drop in the HT Multiplier from 5x to 4x.
A reference clock of 295 required a drop in the HT Multiplier from 4x to 3x.
At a reference clock of 335, a 2 minute Orthos test failed. Dropping the HT Multiplier did not regain stability, so my max reference clock is around 330 with a 3x HT Multiplier.

Obviously your values will be different, this is just an example. But in this example, the 2 minute Orthos test must have passed at 330MHz, since we’re only increasing the reference clock by 3-5MHz at a time, and we wouldn’t have increased the reference clock to 335MHz unless it had passed the 2 minute Orthos test at the previous reference clock value. It failed at 335MHz, so we know that’s an unstable value. However, just because it passed a 2 minute Orthos test at 330MHz doesn’t mean its stable at that value. You’d need to pass a 12-24 hour Orthos blend test to be sure it’s stable, so our max reference clock is probably more like 320MHz. If you want, you can keep testing until you find the exact value that can pass a 24 hour Orthos test, but for most overclocks, you can assume that the max reference clock for the board is about 10-20MHz less than the greatest value to pass the 2 minute Orthos Blend Test. So in this example, our max reference clock is probably around 310-320MHz.
White Whale
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post #6 of 14
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Section 5: Isolating the CPU

Now that we’ve thoroughly tested the motherboard and learned its limits, we’ll move on to the CPU.

Every CPU comes with a default CPU multiplier. For most AMD X2 AM2 socket CPU’s, the CPU Multiplier cannot be increased beyond this default multiplier, but it can be lowered. The exceptions to this rule are the Black Edition CPU’s that have an unlocked CPU Multiplier, meaning the CPU Multiplier can be both lowered and raised beyond the default value. Our goal in this next round of testing is to find the max total CPU speed. Total CPU speed is calculated by multiplying the reference clock by the CPU Multiplier. Since our goal is to max out the CPU speed, we’re going to manually set the CPU Multiplier to the highest setting, which is the default multiplier. We’ll then slowly increase the reference clock to overclock the CPU and find out what speed it can really handle.

To isolate the CPU, we’re going to put the memory setting at DDR2 400 and loosen the timings. This will set a high CPU --> memory divider, helping to keep the memory underclocked as we increase the reference clock to max out the CPU.

The motherboard is going to be stressed as the reference clock is increased, there’s no way to completely take the motherboard out of the picture. But since we already tested the motherboard, we know when it’s going to become unstable and what to do to regain stability. Here’s where your notes come in handy. In our example in the previous section, the HT Link became unstable when the reference clock was set to 240MHz, and we had to lower the HT Multiplier from 5x to 4x (lowering the HT Link from 1200MHz to 960MHz) to regain stability. Well as you increase the reference clock to overclock your CPU, you’re going to know that around 240MHz, you’ll have to lower the HT Multiplier from 5x to 4x. If lowering the HT Multiplier still leaves instability, then and only then can you be sure that it’s the CPU that’s unstable and not the motherboard.

When you’re sure that it’s the CPU that’s unstable, you’re going to regain stability by giving the CPU more voltage. It’s usually best to do this in small increments, such as 0.0125v or 0.0250v at a time. Remember that giving the CPU more voltage will increase temperatures. Even a small amount, such as 0.0250v can cause a 1-3*C change in CPU temperature, so keep an eye on load temperatures! Most users agree to keep your temperatures below about 55 degrees Celsius. If you have a good aftermarket CPU cooler, temperatures shouldn’t be a problem. If you’re overclocking on a stock CPU cooler, increasing voltages is not recommended. You might get away with adding as much as 0.0500-0.0750 volts but even that could send your temperatures to dangerous levels that can shorten the lifespan of your CPU. Decent CPU coolers, such as the AC Freezer 64 Pro, cost as little as $20. Better coolers can cost as much as $45, but there really isn’t any reason to spend more than that.

Assuming you have an aftermarket cooler, you should be safe increasing the CPU voltage to values as high as 1.4500-1.5000v. Many of the temperature monitoring software gives inaccurate data for AM2 socket CPUs, especially the Brisbane cores, so it’s hard to know for sure if your temperatures are ok at this voltage but almost all users should be ok in this range. Anything over 1.5000v is asking for trouble and I wouldn’t recommend it on air cooling. If you really want your computer to last a long time, err on the conservative side and don’t give the CPU more than 1.4500v. Ok, enough talk, let’s get to the overclocking process! Set your computer to the following settings:

Reference Clock: 200
CPU Multiplier: The default value for your CPU (which should be the max CPU multiplier allowed, assuming you do not have a 5000+ Black Edition CPU)
HT Multiplier: 5x
CPU Voltage: 1.3500v
Memory Setting: DDR2 400
Memory Timings: 5-5-5-18-26-2T
Memory Voltage: Whatever the default voltage is for your memory, you should have already researched and figured this out before attempting to overclock.
Motherboard Voltage: Whatever the default voltage is for your motherboard, you should have already researched and figured this out before attempting to overclock.

Save the settings, restart the computer, and run CPU-Z to verify that the settings took effect. Now perform the following steps:

1) Increase the reference clock by 3-5MHz, go to step 2.
2) Once the computer restarts with the new settings, run an Orthos Small FFT Test for 2 minutes. If Orthos ran for 2 minutes with no errors, return to step 1. If Orthos failed before the 2 minutes was up, go on to step 3.
3) Check your notes from the motherboard test. Your reference clock may be at a value that requires a drop in the HT Multiplier. If it is, drop the HT Multiplier by 1x and go to step 5. If you’re sure the HT Multiplier doesn’t need to be lowered yet, go to step 4.
4) Raise the CPU voltage by 0.0250v, then go to step 5. NOTE: I recommend that you do not increase the CPU voltage beyond 1.5000v.
5) Once the computer restarts with the new settings, run an Orthos Small FFT Test for 2 minutes. If Orthos ran for 2 minutes with no errors, return to step 1. If Orthos failed before the 2 minutes was up, go to step 4.

After following those steps, you’ll eventually end up with the following situation: At your default CPU Multiplier, you reached a value for the reference clock that failed a 2 minute Orthos Small FFT Test, but your CPU voltage is maxed out at 1.5000v (or whatever voltage you decided you’re comfortable with). Obviously the CPU is not stable, so the following steps should now be followed:

1) Lower the reference clock by 1-3MHz, go to step 2.
2) Once the computer restarts with the new settings, run an Orthos Small FFT Test for as long as you can. If it fails before 24 hours, go to step 1. If it passes 24 hours, record the total CPU speed (reference clock x CPU Multiplier). This is your max total CPU speed.

If you have a cheap motherboard that had a very low max reference clock, you might encounter an unfortunate situation. The situation I speak of is that you’ve reached the max stable reference clock of your motherboard (with the max CPU Multiplier), but your CPU still has some headroom, meaning it’s still running stable at a voltage lower than 1.5000v. This is a sad situation because you won’t be able to overclock the CPU further without getting a new higher quality motherboard. This is because the CPU Multiplier is already maxed out for your CPU, and the reference clock can’t go any higher without creating instability on the motherboard. This is a rare situation as any respectable motherboard can hit a reference clock of 300MHz or higher, but if you bought a cheap no-name motherboard and a CPU with a low max CPU Multiplier (like the X2 4000+ than can’t go past 10.5x) then you might encounter this problem. But not you, you played it smart and let OCN review your build before you bought anything, didn’t you? 
White Whale
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post #7 of 14
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Section 6: Isolating the Memory

By now, you know a lot about the limits of your motherboard and CPU, and you’re ready to see what your memory can do.

The speed of your memory is calculated by the following equation:

Memory speed = (total CPU speed)/divider

Our goal is to see how fast we can make the memory go, so we want to maximize memory speed. There’s two ways to increase the memory’s speed: 1) Increase the total CPU speed or 2) decrease the divider. Your total CPU speed can only go as high as the number you found in the previous chapter, and the divider can only be as low as 5. You know how to increase the total CPU speed (we just spent an entire chapter doing that), but how do you set the divider? Well, the divider is chosen by the computer based on two factors: a) Memory Setting and b) CPU Multiplier. There is no divider option in any BIOS, you instead manipulate it by changing the Memory Setting and/or the CPU Multiplier. I address this topic in detail in the AMD Memory section of this forum, and you can view it by clicking here.

After reading and absorbing that information, you should have a better idea of how the memory works and how to manipulate it. If you reference the memory divider charts provided by CWell1337, you’ll see that no matter how low we drop the CPU Multiplier, and no matter which memory setting we use, we can never achieve a divider lower than 5. Remember, to maximize memory speed, we want to lower the divider AND increase total CPU speed. So when testing for maximum memory speed, we’ll choose the highest CPU Multiplier that keeps the low divider of 5. If you have DDR2 800 memory (which most people have), then a CPU Multiplier of 10x achieves this. If you have DDR2 667 memory, a CPU Multiplier of 8x achieves this. If you have DDR2 533 memory, who are you and what are you doing with your life? Go spend $30 and get a 2x1GB set of Crucial Ballistix DDR2 800, you won’t regret it.

Hopefully your knowledge of socket AM2 and DDR2 memory is growing, and that you’re ready to start overclocking the memory. Set your computer to the following settings, assuming you have a set of DDR2 800 RAM rated for 4-4-4-12 timings:

Reference Clock: 200
CPU Multiplier: 10x
HT Multiplier: 5x
CPU Voltage: 1.5000v
Memory Setting: DDR2 800
Memory Timings: 4-4-4-12-24-2T
Memory Voltage: Whatever the default voltage is for your memory, you should have already researched and figured this out before attempting to overclock.
Motherboard Voltage: The lowest voltage that allowed you to reach your max reference clock value.

Save the settings, restart the computer, and run CPU-Z to verify that the settings took effect. Now perform the following steps:

1) Increase the reference clock by 3-5MHz, go to step 2.
2) Once the computer restarts with the new settings, run an Orthos Large FFT Test for 2 minutes. If Orthos ran for 2 minutes with no errors, return to step 1. If Orthos failed before the 2 minutes was up, go on to step 3.
3) Check your notes from the motherboard test. Your reference clock may be at a value that requires a drop in the HT Multiplier. If it is, drop the HT Multiplier by 1x and go to step 5. If you’re sure the HT Multiplier doesn’t need to be lowered yet, go to step 4.
4) Loosen the timings to 5-5-5-15-26-2T and go to step 2. If the timings are already set to these values, go to step 5.
5) Increase the memory voltage by 0.100v. NOTE: I do not recommend giving your memory more than 0.100v beyond the default recommended voltage, so only perform this step once. For example, Crucial Ballistix are rated at 2.2v and should not be given more than 2.3v. If you’ve researched your specific set of memory and are confident that it can take more voltage, then you can do so at your own risk. Go to step 6.
6) Lower the reference clock by 1-3MHz, then run an Orthos Large FFT Test for 4 hours. If you pass, then record your settings, this is approximately the max speed of your memory (give or take a few MHz). If you failed the Orthos test before 4 hours is completed, repeat this step.

If you have good memory and a not-so-good CPU, you might reach your max total CPU speed before your memory shows signs of weakness at 5-5-5-15-26-2T. In that case, you know that your overclock will not be memory limited 
White Whale
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post #8 of 14
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Section 7: Combining Your Results

Congratulations, you’re almost done! You now know the max total CPU speed, the max reference clock of your motherboard, and the reference clock values that require either a drop in the HT Multiplier, a loosening of the memory timings, and/or a bump in voltage to either the CPU or memory. Our goal now is to bring it all together and overclock the entire system for good.

It’s nearly impossible for me to tell you exactly how to combine the results from the previous three sections as everyone’s results from the previous three sections are so different. The most basic overclock involves using the default CPU multiplier and adjusting the reference clock, CPU voltage, HT multiplier, and motherboard voltage to achieve the max total CPU speed. Then adjust the memory setting, timings, and voltage to get the fastest memory speed at that CPU speed. However, using the results from isolating each part individually, you can adjust the settings to fine tune your system to your needs. And if you need help, there’s plenty of people here to help you! Good luck!
White Whale
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post #9 of 14
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Section 8: Miscellaneous

The overclocking guide has been turned into PDF form thanks to magus.tsf. Feel free to print it off for reference while you overclock. Please note that the links in this guide obviously won't work in paper form . Also, this PDF reflects the guide as of April 2008, and will not contain any changes made to the guide after that date.

Overclocking Guide in PDF Form

EDIT: Thank you to mixmasterlooney for providing us with a web site to host the PDF files.
Edited by durch - 8/10/08 at 8:07am

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