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AMD Overclocking Guide - October 2002

By: Mike Wright | Guides | Posted: Oct 5, 2002 4:00 am

Frequency/Voltage Control



Now comes the part that many of you have been waiting for; the adjustments to the processor speeds and voltage settings. We'll cover FSB settings and multipliers first so that you'll be familiar with them. Then we'll talk a bit about some of the voltage settings that are available and what they can do for you.


- CPU Settings


If you have a motherboard with an Award BIOS installed, then the first thing you'll want to do here is to disable the Auto Detect. If you have any BIOS that has an automatic detection of the processor, then you'll want to disable it. This opens up a huge window for your overclocking pleasure. Once this setting has been disabled, we can begin our minor surgery.


Spread Spectrum


This is one of those questionable settings, but you can play with it if you like. In theory, this is supposed to reduce the EMI (Electro-Magnetic Interference) within your system. Your call.


CPU Clock


The default number shown here will be determined by what you set the DRAM Clock at. Since you have hopefully set it to 133MHz, this value will appear in this block. But since we have just disabled the Auto Detect already, we can now make changes to this setting. Don't be terribly concerned if you fail to boot after playing with this setting. Just reset the CMOS values and try again with a little lower value.


Depending on what variety of motherboard you have to work with, you will have several options in regards to adjusting the FSB speed. Some of the older motherboards have a very limited set of speed options, so success may be difficult. But most newer motherboards created for the enthusiast will have settings available in 1MHz increments. If you're looking for a motherboard to replace your current dinosaur, then make sure that the settings allow for 1MHz incremental speed adjustments. This will give you the best chance for a good overclock on your system.


If you are restricted to a DRAM Clock setting of 100MHz, then it is unlikely that you will be able to adjust the FSB to anything higher than 112-113MHz. This seems to be a limitation of the motherboard chipset more than anything, but try to get higher if you can. For those with the DRAM Clock set to 133MHz, then you can probably start off your overclocking ventures with a setting of around 145MHz. There are few boards that will not work nicely at this speed, so it makes for a good starting place.


From there, you'll just want to adjust the speed upwards incrementally in 2-3MHz jumps until you start running into system instabilities. Once you start getting crashes occurring, bump it back until they disappear. By this time, you should find yourself running a good bit faster than default.


CPU Ratio


This is where we get to start playing with fire. CPU Ratio simply means processor multiplier. Since we talked earlier about what this means, it is time to talk about setting this value to make the most of your processing potential.


It should be noted up front that adjusting this setting will require a modification to your processor (called Unlocking) that will immediately void the warranty! If you feel uncomfortable with this concept, then you should probably stop right here and be happy with the FSB overclocking and BIOS tweaks that we have already covered. But if you are the adventurous type, then please continue on and we'll talk about Multiplier Manipulation. Fear not, we will cover the actual unlocking process later in this guide.


Well, after that introduction to this portion of the guide, the actual process involved will seem almost anticlimactic. The default value is "Auto" (of course), so you'll just have to change the value to another setting. The available options will again depend on your motherboard. Common allowable settings will normally be in the range of 6x - 13x, but there are motherboards that will allow for higher multiplier settings.


To set these values, just make the change and exit the BIOS saving the changes made. Boot up and make sure that system will run in a stable manner and then make more adjustments if desired. But here is where things get interesting since there are two schools of thought on this method of overclocking.


The first school of thought says that you should run the multiplier as high as you can and then adjust the FSB to a level that gives you the most performance at this higher multiplier setting. While this will give you some decent results, it is limiting since it will not allow you to take the FSB to the next level. If you'll remember a statement I made earlier, the multiplier forces only the processor to create the extra power. Since you can't crank up the FSB to extreme settings, the rest of the system will play a minimal role in your overall performance gain. This school of thought is, however, a widely used method for those with older chipsets in their motherboards (pre KT266A).


The second school of thought is a little more to my liking. It says that you should LOWER the multiplier. And yes, I understand that the lowering of the multiplier would be causing lower speeds, but this is before we adjust the FSB. With the newer chipsets being very agreeable to awesome FSB speeds, there has been a new window opened in the overclocking arena. FSB speeds of 160MHz and beyond have become nearly commonplace. That's right, I said 160MHz! This type of setting would never be attainable with a multiplier setting of 12x, but by lowering the multiplier we can reach new levels or performance.


Something else to consider is that many of these motherboards have new BIOS revisions available that will allow for FSB speeds of 166MHz while retaining the default AGP/PCI/ISA speeds. With a little experimentation, you may just be able to reach levels of performance that you only dreamed of before.


It should be noted that some older motherboards don't have BIOS settings for these values. If this description fits your motherboard, then you may be able to overclock still by means of some jumper switches or dip switches that may be located on your board. Check your users manual for specific locations of these switches and what settings are allowed.


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