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AMD Overclocking Guide - October 2002

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

- Voltage Settings



Though not all motherboards allow you to set the voltages for all components, there are three main areas that we will look at:


VCore - Adjustment of voltage to the processor


VDIMM - Adjustment of voltage to the memory


VAGP - Adjustment of voltage to the AGP video card




Default voltage for the Thunderbird and Palomino based Athlon XP processors is 1.75v while the default voltage is 1.65v for the newer Thoroughbred based Athlon XP chips. Since most motherboards give us some leeway in this setting, we can boost the juice up just a bit to aid us in our overclocking endeavors. But why boost the voltage?


When your processor sends data to any other area of your system, it does so my means of electrical signals. These data streams can sometimes start picking up interference from other system components. By raising the voltage to a given portion of the system, it strengthens this signal and makes it clearer on the other end. It is generally considered safe to raise the core voltage to 1.85v on your Thunderbird or Athlon XP processor. This is the maximum that most motherboards will support unless you perform a voltage hack. We won't be going into that area in this guide, but there are several available online if you look around for them. And if you're interested, there is one motherboard manufacturer that allows for higher voltages without a hack; Shuttle. Many of their product line allow for voltage settings of up to 2.3v through the BIOS, but be warned that anything over 1.85v can lead to some severe damage or destruction to the processor unless you start looking into water, peltier or LN2 cooling techniques.


But before you start cranking that voltage setting all the way up, you will need to use a bit of common sense and care. By raising the voltage, you are creating more heat. While this won't cause a huge problem if you have adequate cooling already in place, you can create a great deal of havoc in your system if the cooling setup is only mediocre, or worse, if it is really bad. Excess heat can lead to the early demise of your processor. If you happen to be looking for an excuse to upgrade, then this may be an ideal way to finally talk yourself into it. But if you happen to enjoy your current rig, then you may be looking forward to forking out more hard-earned cash for a new heart to the system. That said, let's look at some general Safe Zones, or temperature ranges that can be considered satisfactory to the long life of your processor.


Processor temperatures of under 55 Celsius won't cause any serious stability issues to a normal, well-ventilated system. I personally go for 45 Celsius as my maximum, but that is my own personal limitations. I have seen system run at 60-65 Celsius and have no problems, but that is starting to get into a possibly dangerous range so I will always recommend something more sensible.




Looking back at the reasoning for raising voltages, the memory will be our next area of interest for these same reasons. And when you consider that the processor and memory communicate directly by means of the Front Side Bus (FSB), it becomes even clearer why we would want to boost the voltage a bit.


Before we start giving recommended voltage values, the first thing you need to look at is the type of memory that your system uses. Since we're talking AMD processors here, you'll be limited to two basic types of memory modules, PC100/PC133 SDRAM or any of the various types of DDR SDRAM. It is vital that you determine which type of module you use since the voltages are significantly different between them.


For those using PC100/PC133 SDRAM, you'll find your default voltage to be 3.3v. Your motherboard will be the determining factor as to how high you can raise this value (if at all), but a generally useful and safe setting is 3.6 - 3.7v. You may be able to go a bit higher by using an active cooler on the memory modules themselves, but I don't generally recommend them on SDRAM based systems.


For those who have made the leap to a DDR based system, you will find your default voltage for memory to be 2.5v. Again, the motherboard will be the limiting factor in your adjustments to this value, but 2.7 - 2.8v is generally accepted as being a safe zone. I've seen higher voltages attained with perfect stability by using active cooling on the memory modules. There are a few good active coolers out there, so if you decide to go this route, just get one from a reputable company.




Though this doesn't deal directly with the actual system speeds, I have included it because more and more people are discovering the added performance that becomes available when they overclock their video cards. For the HOW-TO of overclocking the nVidia based video cards, check out TweakTown's Beginners Guide to Overclocking nVidia Video Cards. For those with a different type of graphics board, you should be able to find any number of overclocking references online.


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