QuietIce
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- May 7, 2006
- Location
- Anywhere but there
As infinitevalence noted in his thread, this is not the definitive guide to over-clocking as much as a personal, down & dirty method to get to the tweaking stage. I personally want to thank infinitevalence for the hours of time I by-passed using his basic methods and hope he takes no offense at this obvious high-jack of his short-cuts. They've served me well over the years and I honestly appreciate it, as should everybody who learned this system the way I did!
This thread is all about new OC'ers to the AM2 platform. I'll try to keep this and the following five posts updated as I'm able.
If you have suggestions, comments, or additions on how to make this thread better or easier for beginners I'm all ears!
Legal Disclaimer: Note that changing values in BIOS can cause damage to your computer hardware! Overclocking is not manufacturer friendly and most manufacturer warranties do not cover components that have been over-clocked! Neither the author nor anybody associated with OCForums.com is responsible for hardware damage!
(You know I had to do that.)
Another OC Thread?!?
Anybody looking at how to get started overclocking (OC'ing) has probably seen infinitevalence's thread on the A64. I used this very thread to get through my first OC and it taught me a LOT about A64 systems in the process. But that was almost two years ago when the socket 939 platform was king. Over these two years the AM2 platform has become dominant in the AMD world with AM2+ already released. A64 K8's are the CPU of the AM2 platform as they are for the s939 platform, but the sub-systems around the CPU have changed a little and many things in the original thread are confusing to newer over-clockers looking for help. This thread is an attempt to update the theories and methods posted by infinitevalence, not replace them. I've also been more verbose in some areas to point out little things some may find interesting. If this doesn't interest you that's fine, I made up a "Cheat Sheet" in post#26.
The biggest change is the DDR RAM of s939 being replaced with DDR2 RAM used on AM2 systems, a much cheaper solution today. There have also been experiments with the HT Link leading us to the conclusion that overclocking the Link doesn't really accomplish much on the performance side and certainly not enough to risk losing valuable data! Motherboard naming conventions have also changed and while all of them cannot be covered, hopefully there will be enough information here to lead potential OC'ers in the right direction. With that in mind let's start!
Naming Conventions, BIOS Labels, and Common Values
NOTE: CPU-Z labels are taken from CPU-Z v1.44.1
The System Clock
The crux of the s939, AM2, and AM2+ platforms, the system clock has had many names over the years and is often referred to as the FSB. This is and has been a misnomer since the A64 came out! The closest thing to a "FSB" the A64 has is the HT Link, but more on that later. The system clock (or just "the clock") is a 200 MHz clock which, with help from multipliers and ratios, governs the speed of the CPU, RAM/memory, and HT Link. To adjust the clock setting you often have to find some label usually containing "overclocking", "OC", or "configuration" and set it's value to "Manual" or "User", which will highlight or show other options. The clock is usually adjusted using the "+"/"-" keys or entering a new number from 200-400. CPU-Z labels this the "Bus Speed" (but at least they finally got rid of the "FSB" label!).
CPU Multiplier, Speed, and vCore
The CPU Multiplier (aka CPU multi), when multiplied by the system clock, gives you the CPU speed. CPU speed is the most important part of over-clocking and has the greatest impact on performance bar none - it's the Holy Grail of OC'ing. Most AMD CPUs have a multiplier that is "upward locked", meaning you can't raise the multiplier above the factory setting. The FX and Black Edition series are exceptions to this rule but all others are locked. However, the multiplier can be clocked downward. Most BIOS' use some form of "CPU Multiplier" as a label for this parameter so it should be easy to find. Optional values will start with the default CPU multiplier and go down by 0.5x multipliers.
vCore is electronic short-hand for the CPU Voltage. vCore is labeled vCore, CPU Voltage, Core Voltage, VID and others. It is often found with the other CPU overclock settings but can sometimes be found on it's own page with other system voltages. AFAIK all AM2 CPUs have a default vCore of 1.30-1.35v per AMD specs but options usually range from less than 1.0v up to 1.55v or farther. Some boards have odd voltages with a 0.05v spacing, others are spaced at 0.025v intervals, and others get tighter still to 0.125v. Other boards don't list voltages at all and instead use a "%" method where the extra percent is added to the stock vCore.
NOTE: As with the clock setting you sometimes need to set another value in BIOS to find the CPU configuration options. CPU-Z labels CPU speed as "Core Speed" and vCore as "Core Voltage".
Memory Timings and vDIMM
The Memory Timings are not just for advanced OC'ers, everybody should use them to stabilize their system. Memory timings are often grayed out unless a "MemTiming", "Timing Mode", or "Timing and Configuration" option of "Manual" or "User" is set. The main timings we are concerned with are labeled CAS (or CL), tRCD, tRP, and tRAS. These are the basic timings listed in most RAM specifications and can often be found on the RAM stick in that order. Sometimes the BIOS does not have them in that order, so be careful! CAS, tRCD, and tRP values usually range from 3-10 and tRAS values have a range of 6-24 or more. There are often other timings here which you can explore after checking out the OCF Memory section. For this thread we'll leave these advanced timings on Auto and not mention them again.
vDIMM is also electronic short-hand and is the RAM Voltage or DRAM Voltage. vDIMM is usually located near the vCore in BIOS but sometimes it's with the other RAM settings. vDIMM can be labeled many things including DRAM Voltage, DDR2 Core Voltage, DVID and more. vDIMM is 1.8v default for "normal" DDR2 but performance RAM is often higher than 1.8v. Check the RAM stick or manufacturer's specification sheet for the default vDIMM of your RAM. vDIMM value options can range from 1.7v up to 2.6v or more. vDIMM is not shown in CPU-Z.
RAM Ratio
This has probably caused the most confusion jumping from s939 with DDR to AM2 with DDR2 RAM. It has many names and many numbers associated with it, though they all do the same thing in the same way. The first thing you often have to look for is the memory configuration page. Some labels for this are Memory Mode, Memclock Mode, DRAM Timing, DRAM Config, CPU Config, etc. What you're looking for usually has a "Manual" or "Limit" option that you need to set to show more detailed RAM options. Once you find these you look for DRAM ratio, RAM Divider, Memclock Value, Memory Limit, or any combination of these words. The options are one of three sets of numbers usually containing: (200, 266, 333, 400), OR (400, 533, 667, 800), OR (1:1, 4:3, 5:3, 2:1). Sometimes there are other numbers in addition to those listed. CPU-Z labels this as "FSB : DRAM" and has a value showing CPU/x.
HyperTransport Link
This is another overly-labeled component of the AM2 platform having seen names like HTT, HT Bus, I/O Bus, HT Link, etc. HT Link is the common usage standing for HyperTransport Link and is used by CPU-Z as well. Note this is not the same as HyperThreading on Intel platforms! The HT Link is very close to the "FSB" of Intel platforms, handling all of the system I/O to PCIe, PCI, and USB buses. The CPU to RAM access does not go through the HT Link so changing it's speed does not effect RAM performance. The HT Link multiplier has many labels, K8 <> NB, CPU <> NB, FSB, and HTT are but a few. Common HT Link options are (200, 400, 600, 800, 1000) OR (2X, 3X, 4X, 5X).
That's the basic over-clocking variables for an AM2 rig. Most of these are very simple but sometimes hard to find. If your motherboard manual and the pointers above aren't enough to find what you're looking for just post in the AMD Motherboard Socket AM2 section and I'm sure someone will help. There are other things to adjust and play with but let's stick with those listed for now. Take some time to find all these values and variables in the BIOS and ask questions if you're unsure.
Crawling before Walking
Don't take the title personally. Everybody running an OC'ed rig has been a n00b and learned somewhere, either from hours of experimentation or from others - usually on forums like (ad plug) OCForums.com!
Just open your mind a little, be prepared for some pointing & clicking, learn how to use the arrow keys in BIOS, and this will be easier than you think.
Programs
Over-clocking is about finding the limits of the hardware. The best method known for this is the scientific method and it's just like a high school science lab. First there are several "benchmark" programs (BMs) out there including PCMark and SuperPi for CPUs, 3DMark for video, and Everest for RAM. By running some or all of these BMs before overclocking we can document and study the differences between system default (stock) and overclocked settings, which will be valuable data later when "tweaking" the system for best performance. There are also a few other programs that are nice to have for OC'ing and determining system stability:
CPU-Z, as already mentioned, to keep track of actual values as BIOS settings are changed
MemTest86 is used to determine RAM stability and is included in some BIOS'
Core Temp is a great little program used to keep track of the CPU die temps. AM2 CPUs have some variance in the die sensor and usually are not the same between two cores of a dual-core CPU. The sensors can also be off as "real" temperature readings but are very good for calculating differences in temps on the same core.
Prime95 or Orthos is used to "load" the CPU (make it work as hard as possible). If Prime95 is used with a dual-core CPU make sure you have version 25.1 or newer to support dual-core CPUs OR make two folders and run them both at the same time setting affinity for the different cores. Prime95/Orthos (P95) creates high CPU temperatures and, if pushed far enough, will cause a shut-down of the system if temps get too high. Make sure you have the CPU temperature shut-down in the BIOS set ON to avoid any CPU damage! And pick a low number like 70°C (~160°F) - most AM2 CPUs shouldn't normally run above 65°C.
ClockGen or a board manufacturer's program to set system hardware variables in Windows/Linux. While this is not required for OC'ing it can sure save some reboots and time while doing it!
Having decided on BM programs go ahead and run them while the system is still stock. Note the CPU-Z values as well. Write down the settings and record the BM scores under them, you'll want them later to see how much you've accomplished!
Manual Entry and BIOS
After running the stock BMs and recording the scores reboot the computer and enter BIOS. Find the above variables, set them all to manual entry, and enter the system default (stock) values for each. This is done because the BIOS has a very nasty habit of adjusting values on reboot if they are left on Auto or Default. Just like a lab experiment the idea is to change one variable at a time and Auto values can mess that up. The default values for common system components are:
System Clock: 200 MHz
CPU Multiplier: CPU rating divided by 200 (i.e., a 2400 MHz CPU will be 2400/200 = 12)
vCore: 1.35v
RAM ratio: 400 OR 800 OR 2:1 (depending on the BIOS list values)
vDIMM: 1.8v (but may be as high as 2.1v)*
RAM timings: This is the stock timings of the RAM as noted in it's specifications (4-4-4-12, 5-5-5-15, etc.)*
*RAM timings and vDIMM are often printed on the side of the RAM stick and can always be found on the manufacturer's website
HT Link: 1000 MHz OR 5X (depending on the BIOS list values)
While in the BIOS also turn off CoolnQuiet (CnQ) and any CPU or system fan regulators. CnQ is found in a number of places in BIOS and allows the BIOS to change the CPU multiplier and vCore depending on the CPU load. It might be good for future use after over-clocking but not during. CPU and system fan regulators aren't a bad thing either, but it's better to keep the components as cool as possible right now so turn them off and turn them on afterwords if desired.
Final Stock Systems Check
Reboot the system just to make sure everything is running as it should be after the manual entry. Most motherboards have a drop in vCore between BIOS and idling (some worse than others) so run CPU-Z and note the vCore (Core Voltage) shown. Leave CPU-Z up and running, start Core Temp, then record the CPU idle temp(s). Leave CPU-Z and Core Temp open and start P95 - the CPU temp(s) should increase almost immediately. Wait a couple of seconds for the temps to stabilize a little and write down the load temps under the idle temps just recorded. (If the CPU is water cooled temps may take several minutes to stabilize.) Also, record the load vCore reading by CPU-Z. Compare the idle vCore to the load vCore - the difference between them is known as vDroop and is quite common on all systems (even Intel). A vDroop of 0.03v or less is fine, 0.03-0.05v is average. Over 0.05v is not so good but if it's steady it's workable. The real problems come from a load and/or idle vCore that jumps around a lot - greater than 0.05v up and down as you watch it with CPU-Z is NOT good and may effect your OC. Motherboard power chips (MOSFETs) and under-rated power supplies are often the culprits for this behavior.
The First Steps
The factory system and settings are still at stock values but now there's a little control over them. BIOS can't change the important values on it's own anymore and data is recorded about the stock configuration. It's time to move on in the OC experiment and start checking out individual hardware components one by one. While this is easy enough it is time consuming and other component values need changing to make sure they can't interfere with the component being tested. Since the clock is the focal point of the system experimenting starts there ...
This thread is all about new OC'ers to the AM2 platform. I'll try to keep this and the following five posts updated as I'm able.
If you have suggestions, comments, or additions on how to make this thread better or easier for beginners I'm all ears!
Legal Disclaimer: Note that changing values in BIOS can cause damage to your computer hardware! Overclocking is not manufacturer friendly and most manufacturer warranties do not cover components that have been over-clocked! Neither the author nor anybody associated with OCForums.com is responsible for hardware damage!
(You know I had to do that.)
Another OC Thread?!?
Anybody looking at how to get started overclocking (OC'ing) has probably seen infinitevalence's thread on the A64. I used this very thread to get through my first OC and it taught me a LOT about A64 systems in the process. But that was almost two years ago when the socket 939 platform was king. Over these two years the AM2 platform has become dominant in the AMD world with AM2+ already released. A64 K8's are the CPU of the AM2 platform as they are for the s939 platform, but the sub-systems around the CPU have changed a little and many things in the original thread are confusing to newer over-clockers looking for help. This thread is an attempt to update the theories and methods posted by infinitevalence, not replace them. I've also been more verbose in some areas to point out little things some may find interesting. If this doesn't interest you that's fine, I made up a "Cheat Sheet" in post#26.
The biggest change is the DDR RAM of s939 being replaced with DDR2 RAM used on AM2 systems, a much cheaper solution today. There have also been experiments with the HT Link leading us to the conclusion that overclocking the Link doesn't really accomplish much on the performance side and certainly not enough to risk losing valuable data! Motherboard naming conventions have also changed and while all of them cannot be covered, hopefully there will be enough information here to lead potential OC'ers in the right direction. With that in mind let's start!
Naming Conventions, BIOS Labels, and Common Values
NOTE: CPU-Z labels are taken from CPU-Z v1.44.1
The System Clock
The crux of the s939, AM2, and AM2+ platforms, the system clock has had many names over the years and is often referred to as the FSB. This is and has been a misnomer since the A64 came out! The closest thing to a "FSB" the A64 has is the HT Link, but more on that later. The system clock (or just "the clock") is a 200 MHz clock which, with help from multipliers and ratios, governs the speed of the CPU, RAM/memory, and HT Link. To adjust the clock setting you often have to find some label usually containing "overclocking", "OC", or "configuration" and set it's value to "Manual" or "User", which will highlight or show other options. The clock is usually adjusted using the "+"/"-" keys or entering a new number from 200-400. CPU-Z labels this the "Bus Speed" (but at least they finally got rid of the "FSB" label!).
CPU Multiplier, Speed, and vCore
The CPU Multiplier (aka CPU multi), when multiplied by the system clock, gives you the CPU speed. CPU speed is the most important part of over-clocking and has the greatest impact on performance bar none - it's the Holy Grail of OC'ing. Most AMD CPUs have a multiplier that is "upward locked", meaning you can't raise the multiplier above the factory setting. The FX and Black Edition series are exceptions to this rule but all others are locked. However, the multiplier can be clocked downward. Most BIOS' use some form of "CPU Multiplier" as a label for this parameter so it should be easy to find. Optional values will start with the default CPU multiplier and go down by 0.5x multipliers.
vCore is electronic short-hand for the CPU Voltage. vCore is labeled vCore, CPU Voltage, Core Voltage, VID and others. It is often found with the other CPU overclock settings but can sometimes be found on it's own page with other system voltages. AFAIK all AM2 CPUs have a default vCore of 1.30-1.35v per AMD specs but options usually range from less than 1.0v up to 1.55v or farther. Some boards have odd voltages with a 0.05v spacing, others are spaced at 0.025v intervals, and others get tighter still to 0.125v. Other boards don't list voltages at all and instead use a "%" method where the extra percent is added to the stock vCore.
NOTE: As with the clock setting you sometimes need to set another value in BIOS to find the CPU configuration options. CPU-Z labels CPU speed as "Core Speed" and vCore as "Core Voltage".
Memory Timings and vDIMM
The Memory Timings are not just for advanced OC'ers, everybody should use them to stabilize their system. Memory timings are often grayed out unless a "MemTiming", "Timing Mode", or "Timing and Configuration" option of "Manual" or "User" is set. The main timings we are concerned with are labeled CAS (or CL), tRCD, tRP, and tRAS. These are the basic timings listed in most RAM specifications and can often be found on the RAM stick in that order. Sometimes the BIOS does not have them in that order, so be careful! CAS, tRCD, and tRP values usually range from 3-10 and tRAS values have a range of 6-24 or more. There are often other timings here which you can explore after checking out the OCF Memory section. For this thread we'll leave these advanced timings on Auto and not mention them again.
vDIMM is also electronic short-hand and is the RAM Voltage or DRAM Voltage. vDIMM is usually located near the vCore in BIOS but sometimes it's with the other RAM settings. vDIMM can be labeled many things including DRAM Voltage, DDR2 Core Voltage, DVID and more. vDIMM is 1.8v default for "normal" DDR2 but performance RAM is often higher than 1.8v. Check the RAM stick or manufacturer's specification sheet for the default vDIMM of your RAM. vDIMM value options can range from 1.7v up to 2.6v or more. vDIMM is not shown in CPU-Z.
RAM Ratio
This has probably caused the most confusion jumping from s939 with DDR to AM2 with DDR2 RAM. It has many names and many numbers associated with it, though they all do the same thing in the same way. The first thing you often have to look for is the memory configuration page. Some labels for this are Memory Mode, Memclock Mode, DRAM Timing, DRAM Config, CPU Config, etc. What you're looking for usually has a "Manual" or "Limit" option that you need to set to show more detailed RAM options. Once you find these you look for DRAM ratio, RAM Divider, Memclock Value, Memory Limit, or any combination of these words. The options are one of three sets of numbers usually containing: (200, 266, 333, 400), OR (400, 533, 667, 800), OR (1:1, 4:3, 5:3, 2:1). Sometimes there are other numbers in addition to those listed. CPU-Z labels this as "FSB : DRAM" and has a value showing CPU/x.
HyperTransport Link
This is another overly-labeled component of the AM2 platform having seen names like HTT, HT Bus, I/O Bus, HT Link, etc. HT Link is the common usage standing for HyperTransport Link and is used by CPU-Z as well. Note this is not the same as HyperThreading on Intel platforms! The HT Link is very close to the "FSB" of Intel platforms, handling all of the system I/O to PCIe, PCI, and USB buses. The CPU to RAM access does not go through the HT Link so changing it's speed does not effect RAM performance. The HT Link multiplier has many labels, K8 <> NB, CPU <> NB, FSB, and HTT are but a few. Common HT Link options are (200, 400, 600, 800, 1000) OR (2X, 3X, 4X, 5X).
That's the basic over-clocking variables for an AM2 rig. Most of these are very simple but sometimes hard to find. If your motherboard manual and the pointers above aren't enough to find what you're looking for just post in the AMD Motherboard Socket AM2 section and I'm sure someone will help. There are other things to adjust and play with but let's stick with those listed for now. Take some time to find all these values and variables in the BIOS and ask questions if you're unsure.
Crawling before Walking
Don't take the title personally. Everybody running an OC'ed rig has been a n00b and learned somewhere, either from hours of experimentation or from others - usually on forums like (ad plug
) OCForums.com!Just open your mind a little, be prepared for some pointing & clicking, learn how to use the arrow keys in BIOS, and this will be easier than you think.
Programs
Over-clocking is about finding the limits of the hardware. The best method known for this is the scientific method and it's just like a high school science lab. First there are several "benchmark" programs (BMs) out there including PCMark and SuperPi for CPUs, 3DMark for video, and Everest for RAM. By running some or all of these BMs before overclocking we can document and study the differences between system default (stock) and overclocked settings, which will be valuable data later when "tweaking" the system for best performance. There are also a few other programs that are nice to have for OC'ing and determining system stability:
CPU-Z, as already mentioned, to keep track of actual values as BIOS settings are changed
MemTest86 is used to determine RAM stability and is included in some BIOS'
Core Temp is a great little program used to keep track of the CPU die temps. AM2 CPUs have some variance in the die sensor and usually are not the same between two cores of a dual-core CPU. The sensors can also be off as "real" temperature readings but are very good for calculating differences in temps on the same core.
Prime95 or Orthos is used to "load" the CPU (make it work as hard as possible). If Prime95 is used with a dual-core CPU make sure you have version 25.1 or newer to support dual-core CPUs OR make two folders and run them both at the same time setting affinity for the different cores. Prime95/Orthos (P95) creates high CPU temperatures and, if pushed far enough, will cause a shut-down of the system if temps get too high. Make sure you have the CPU temperature shut-down in the BIOS set ON to avoid any CPU damage! And pick a low number like 70°C (~160°F) - most AM2 CPUs shouldn't normally run above 65°C.
ClockGen or a board manufacturer's program to set system hardware variables in Windows/Linux. While this is not required for OC'ing it can sure save some reboots and time while doing it!
Having decided on BM programs go ahead and run them while the system is still stock. Note the CPU-Z values as well. Write down the settings and record the BM scores under them, you'll want them later to see how much you've accomplished!
Manual Entry and BIOS
After running the stock BMs and recording the scores reboot the computer and enter BIOS. Find the above variables, set them all to manual entry, and enter the system default (stock) values for each. This is done because the BIOS has a very nasty habit of adjusting values on reboot if they are left on Auto or Default. Just like a lab experiment the idea is to change one variable at a time and Auto values can mess that up. The default values for common system components are:
System Clock: 200 MHz
CPU Multiplier: CPU rating divided by 200 (i.e., a 2400 MHz CPU will be 2400/200 = 12)
vCore: 1.35v
RAM ratio: 400 OR 800 OR 2:1 (depending on the BIOS list values)
vDIMM: 1.8v (but may be as high as 2.1v)*
RAM timings: This is the stock timings of the RAM as noted in it's specifications (4-4-4-12, 5-5-5-15, etc.)*
*RAM timings and vDIMM are often printed on the side of the RAM stick and can always be found on the manufacturer's website
HT Link: 1000 MHz OR 5X (depending on the BIOS list values)
While in the BIOS also turn off CoolnQuiet (CnQ) and any CPU or system fan regulators. CnQ is found in a number of places in BIOS and allows the BIOS to change the CPU multiplier and vCore depending on the CPU load. It might be good for future use after over-clocking but not during. CPU and system fan regulators aren't a bad thing either, but it's better to keep the components as cool as possible right now so turn them off and turn them on afterwords if desired.
Final Stock Systems Check
Reboot the system just to make sure everything is running as it should be after the manual entry. Most motherboards have a drop in vCore between BIOS and idling (some worse than others) so run CPU-Z and note the vCore (Core Voltage) shown. Leave CPU-Z up and running, start Core Temp, then record the CPU idle temp(s). Leave CPU-Z and Core Temp open and start P95 - the CPU temp(s) should increase almost immediately. Wait a couple of seconds for the temps to stabilize a little and write down the load temps under the idle temps just recorded. (If the CPU is water cooled temps may take several minutes to stabilize.) Also, record the load vCore reading by CPU-Z. Compare the idle vCore to the load vCore - the difference between them is known as vDroop and is quite common on all systems (even Intel). A vDroop of 0.03v or less is fine, 0.03-0.05v is average. Over 0.05v is not so good but if it's steady it's workable. The real problems come from a load and/or idle vCore that jumps around a lot - greater than 0.05v up and down as you watch it with CPU-Z is NOT good and may effect your OC. Motherboard power chips (MOSFETs) and under-rated power supplies are often the culprits for this behavior.
The First Steps
The factory system and settings are still at stock values but now there's a little control over them. BIOS can't change the important values on it's own anymore and data is recorded about the stock configuration. It's time to move on in the OC experiment and start checking out individual hardware components one by one. While this is easy enough it is time consuming and other component values need changing to make sure they can't interfere with the component being tested. Since the clock is the focal point of the system experimenting starts there ...
Last edited:
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