*Note* - I am not responsible if your damage your PC from overclocking. Overclocking your PC can reduce lifespan of your components so do it at your own risk.
Introduction
Overclocking on an AMD platform can be slightly different than overclocking on an Intel platform simply because of different architectures both in the cpu and the motherboard. The main difference when overclocking in AMD is that you have to worry about an extra frequency called Hypertransport. Before we start, we will need some essential programs that will help us determine clock speeds, overclock reliability, and temperatures because we don't want to burn up our cpu in the proccess. There are many other programs to use out there but these are my favorites!
Important Overclocking Tools
CPU-Z, this program helps you determine clocks of your cpu, hypertransport, RAM, FSB, etc.
Everest Home edition is a free program to help you monitor temperatures of your CPU. This program will also tell you various clocks in your system but I like CPU-Z better
Prime 95, is a program that basically will put your cpu's at maximum load for however long you want. The reason why we will be doing this is to 1)Test your cpu reliability at a particular overclock 2) monitor the temperature of your cpu at its highest load.
Anyway, with these importantly basic tools, we can begin overclocking our AMD platform. But first, we must determine how each clock speed is determined on your system.
A64 Mathematics
The Reference Bus or Front Side Bus on an AMD platform is basically the main clock of the motherboard which determines the clocks of every other component. The default speed of this bus is 200 Mhz.
Calculating the CPU clock speed
Reference Bus * CPU multiplier = CPU Clock speed
Example: 200Mhz * 9 = 1800Mhz (1.8 Ghz)
When overclocked, your system will look more like this
OC Example: 250Mhz * 9 = 2250Mhz (2.25 Ghz)
At this point your probably like, why bother going through all the trouble to increase your Reference clock if you can just change your multiplier of the CPU and call it a day?!? CPU manufacturers lock the CPU multiplier from going any higher. You can change the multiplier to a lower multiplier but you cannot go higher on most processors. I believe the "black edition" CPU's are the only modern AMD cpu's with an unlocked multiplier.
Calculating Hypertransport speed
*NOTE* In your BIOS, your hypertransport multiplier will most likely be referred to as HTT, LDT or <K8> to <NB> multiplier.
Reference clock * HTT multiplier = HTTspeed
Example= 200 Mhz * 5 = 1000Mhz
While we are overclocking we want to keep this frequency as close to the default speed as possible. You don't want to go too far over OR under this frequency or your pc will probably be unstable.
OC Example= 250 * 4 = 1000Mhz
How to determine Memory Speed (1:1)
This is pretty easy because if you are not using a memory divider your memory operates at the same speed as your reference clock. A memory divider basically allows you to set different speeds for your memory. This is useful because when you start cranking up your reference clock, your going to want to start lowering your memory speed so it does not exceed its default speeds.
Here is how I have my memory divider set up. I have DDR 500 which is set to run a default speed of 250 Mhz.
Reference clock = 250Mhz
Memory Divider = 200 Mhz
Actual Operating clock = 250 Mhz
As you can see, I lowered my memory frequency by 50 Mhz but increased my reference clock by 50 Mhz which kept the memory at its default speed. I usually just use CPUZ to double check my memory speed after making any changes.
Prepping your machine for Overclocking
Now that we know what frequencies we need to watch out for, lets start overclocking!! Before you start, I would disable the "Cool n quiet" feature (found in bios) and the CPU throttling feature of vista as these can make your overclocked cpu become unstable.
Drop down the HTT multiplier and the memory divider by one step and boot back up into windows and launch CPUZ to make sure your are changing the right settings.
This is the information that you want to be looking at in CPUZ. The CPU Voltage is not important now but it will be later. The most important frequencies to be monitoring are your HT Link (bottom left) and DRAM frequency (right window).
Ignore my settings as this is what my CPUZ looks like when overclocked. This picture is here simply to show you where to look in this program.
Beginning the Overclock Proccess
After you adjusted your HTT link and Reference clock and verified it by CPUZ, boot back into your BIOS and adjust your reference clock by raising it about 10 or 15 Mhz. Since our clock speeds are still low, it is safe to make large adjustments like this. When you boot back into windows, we want to check our frequencies, stability and temperatures. NOTE: If you cannot boot back into windows you should go back and lower your reference clock more and double check your HTT multiplier/memory divider settings, if you cannot even boot into the BIOS you have some serious unstability, but don't panic!! This happened to me plenty of times while trying to overclock. All you need to do is reset your CMOS back to default settings. This can be done by moving the appropriate jumper on your motherboard. If you don't feel like finding out how to do that, like me, you can just unplug your computer and pop off the battery on the motherboard. Wait about 30 seconds or so and reinstall the batter and power cable and you should be back at default settings!
Checking for stability after overclocking
Anyway, this is the appropriate way to check your cpu for stability. For your prime95 test you want to do the maximum heat and power consumption test. Make sure all of your CPU's is at 100% load. We also want to keep an eye on your Temperatures. I would make sure that each individual core does not go over 75*C and the CPU temp should stay below 60*C. Run the Prime 95 test for about 15 - 20 minutes to ensure basic stability.
Continuing the Overclock Proccess
So basically, you just want to keep stepping up your reference clock (while keeping appropriate HTT clocks and memory clocks of course) until your PC gets unstable. Most pc's should reach a 250 Mhz reference bus easily. How much farther you can go from that simply depends on how reliable your particular cpu is.
Bringing CPU Voltage into the equation
So when your computer starts getting unstable by either getting blue screens or failing the prime 95 test, its time to start increasing your CPU voltage! At This point you will have noticed that even after increasing your CPU clock, your temperature will still be very close to the stock temperatures. Maybe only 1 or 2 Celcius higher than normal. Start increasing voltage in VERY small increments until you regain stability again. You'll notice as you increase voltage, it makes a BIG impact on your CPU temperature. Increasing your voltage increases the wear and tear on your cpu so you don't want to just crank it sky high. The stock voltage for my cpu is 1.35V and mine is running at 1.5V which is a pretty big increase. I would probably not suggest going much higher than a .2 volt increase. So as you regain stability, start bumping up the reference clock slowly again. How much farther you want to go is totally up to you and how good your particular cpu is. If you are able to push your cpu up much higher without having to increase your voltage much then it is a good idea to keep going. If you Find yourself having to increase your voltage a lot and you are barely getting a speed increase then it is obviously not worth it. The ideal overclock is to find a happy medium where you have your speed maxed out on a somewhat low voltage. Yes, you can probably get another 20 Mhz if you bumped your voltage from 1.5 to 1.6V but is it worth it, NO. Like I said earlier, voltage greatly increases heat so you want to use the lowest possible setting while still having stability. And of course when you think you found a sweet spot, you want to get your HTT and memory speeds as close to default as possible.
Ensuring Long Term Stability
So far, we've only been doing 15 minute tests in Prime 95. This short term testing really only tells us if your cpu is stable enough to run windows properly. After you have found good overclock settings, let prime 95 run for at least 6 hours. If your temperatures stay within a steady range and your cpu passes the tests, you have achieved a successful overclock! For long term stability, some people let prime 95 run for several days straight to ensure maximum stability. Its totally up to you how long you want to let it run.
Introduction
Overclocking on an AMD platform can be slightly different than overclocking on an Intel platform simply because of different architectures both in the cpu and the motherboard. The main difference when overclocking in AMD is that you have to worry about an extra frequency called Hypertransport. Before we start, we will need some essential programs that will help us determine clock speeds, overclock reliability, and temperatures because we don't want to burn up our cpu in the proccess. There are many other programs to use out there but these are my favorites!
Important Overclocking Tools
CPU-Z, this program helps you determine clocks of your cpu, hypertransport, RAM, FSB, etc.
Everest Home edition is a free program to help you monitor temperatures of your CPU. This program will also tell you various clocks in your system but I like CPU-Z better
Prime 95, is a program that basically will put your cpu's at maximum load for however long you want. The reason why we will be doing this is to 1)Test your cpu reliability at a particular overclock 2) monitor the temperature of your cpu at its highest load.
Anyway, with these importantly basic tools, we can begin overclocking our AMD platform. But first, we must determine how each clock speed is determined on your system.
A64 Mathematics
The Reference Bus or Front Side Bus on an AMD platform is basically the main clock of the motherboard which determines the clocks of every other component. The default speed of this bus is 200 Mhz.
Calculating the CPU clock speed
Reference Bus * CPU multiplier = CPU Clock speed
Example: 200Mhz * 9 = 1800Mhz (1.8 Ghz)
When overclocked, your system will look more like this
OC Example: 250Mhz * 9 = 2250Mhz (2.25 Ghz)
At this point your probably like, why bother going through all the trouble to increase your Reference clock if you can just change your multiplier of the CPU and call it a day?!? CPU manufacturers lock the CPU multiplier from going any higher. You can change the multiplier to a lower multiplier but you cannot go higher on most processors. I believe the "black edition" CPU's are the only modern AMD cpu's with an unlocked multiplier.
Calculating Hypertransport speed
*NOTE* In your BIOS, your hypertransport multiplier will most likely be referred to as HTT, LDT or <K8> to <NB> multiplier.
Reference clock * HTT multiplier = HTTspeed
Example= 200 Mhz * 5 = 1000Mhz
While we are overclocking we want to keep this frequency as close to the default speed as possible. You don't want to go too far over OR under this frequency or your pc will probably be unstable.
OC Example= 250 * 4 = 1000Mhz
How to determine Memory Speed (1:1)
This is pretty easy because if you are not using a memory divider your memory operates at the same speed as your reference clock. A memory divider basically allows you to set different speeds for your memory. This is useful because when you start cranking up your reference clock, your going to want to start lowering your memory speed so it does not exceed its default speeds.
Here is how I have my memory divider set up. I have DDR 500 which is set to run a default speed of 250 Mhz.
Reference clock = 250Mhz
Memory Divider = 200 Mhz
Actual Operating clock = 250 Mhz
As you can see, I lowered my memory frequency by 50 Mhz but increased my reference clock by 50 Mhz which kept the memory at its default speed. I usually just use CPUZ to double check my memory speed after making any changes.
Prepping your machine for Overclocking
Now that we know what frequencies we need to watch out for, lets start overclocking!! Before you start, I would disable the "Cool n quiet" feature (found in bios) and the CPU throttling feature of vista as these can make your overclocked cpu become unstable.
Drop down the HTT multiplier and the memory divider by one step and boot back up into windows and launch CPUZ to make sure your are changing the right settings.
This is the information that you want to be looking at in CPUZ. The CPU Voltage is not important now but it will be later. The most important frequencies to be monitoring are your HT Link (bottom left) and DRAM frequency (right window).
Ignore my settings as this is what my CPUZ looks like when overclocked. This picture is here simply to show you where to look in this program.
Beginning the Overclock Proccess
After you adjusted your HTT link and Reference clock and verified it by CPUZ, boot back into your BIOS and adjust your reference clock by raising it about 10 or 15 Mhz. Since our clock speeds are still low, it is safe to make large adjustments like this. When you boot back into windows, we want to check our frequencies, stability and temperatures. NOTE: If you cannot boot back into windows you should go back and lower your reference clock more and double check your HTT multiplier/memory divider settings, if you cannot even boot into the BIOS you have some serious unstability, but don't panic!! This happened to me plenty of times while trying to overclock. All you need to do is reset your CMOS back to default settings. This can be done by moving the appropriate jumper on your motherboard. If you don't feel like finding out how to do that, like me, you can just unplug your computer and pop off the battery on the motherboard. Wait about 30 seconds or so and reinstall the batter and power cable and you should be back at default settings!
Checking for stability after overclocking
Anyway, this is the appropriate way to check your cpu for stability. For your prime95 test you want to do the maximum heat and power consumption test. Make sure all of your CPU's is at 100% load. We also want to keep an eye on your Temperatures. I would make sure that each individual core does not go over 75*C and the CPU temp should stay below 60*C. Run the Prime 95 test for about 15 - 20 minutes to ensure basic stability.
Continuing the Overclock Proccess
So basically, you just want to keep stepping up your reference clock (while keeping appropriate HTT clocks and memory clocks of course) until your PC gets unstable. Most pc's should reach a 250 Mhz reference bus easily. How much farther you can go from that simply depends on how reliable your particular cpu is.
Bringing CPU Voltage into the equation
So when your computer starts getting unstable by either getting blue screens or failing the prime 95 test, its time to start increasing your CPU voltage! At This point you will have noticed that even after increasing your CPU clock, your temperature will still be very close to the stock temperatures. Maybe only 1 or 2 Celcius higher than normal. Start increasing voltage in VERY small increments until you regain stability again. You'll notice as you increase voltage, it makes a BIG impact on your CPU temperature. Increasing your voltage increases the wear and tear on your cpu so you don't want to just crank it sky high. The stock voltage for my cpu is 1.35V and mine is running at 1.5V which is a pretty big increase. I would probably not suggest going much higher than a .2 volt increase. So as you regain stability, start bumping up the reference clock slowly again. How much farther you want to go is totally up to you and how good your particular cpu is. If you are able to push your cpu up much higher without having to increase your voltage much then it is a good idea to keep going. If you Find yourself having to increase your voltage a lot and you are barely getting a speed increase then it is obviously not worth it. The ideal overclock is to find a happy medium where you have your speed maxed out on a somewhat low voltage. Yes, you can probably get another 20 Mhz if you bumped your voltage from 1.5 to 1.6V but is it worth it, NO. Like I said earlier, voltage greatly increases heat so you want to use the lowest possible setting while still having stability. And of course when you think you found a sweet spot, you want to get your HTT and memory speeds as close to default as possible.
Ensuring Long Term Stability
So far, we've only been doing 15 minute tests in Prime 95. This short term testing really only tells us if your cpu is stable enough to run windows properly. After you have found good overclock settings, let prime 95 run for at least 6 hours. If your temperatures stay within a steady range and your cpu passes the tests, you have achieved a successful overclock! For long term stability, some people let prime 95 run for several days straight to ensure maximum stability. Its totally up to you how long you want to let it run.
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