Intel's Anti-Overclocking Technology Simplified

John Thorensen writes "Found a fantastic article on Intel's recent Anti-Overclocking patent at Fastsilicon.com. Worth the read, as it also explains some of the technical and ethical issues of overclocking. Good to see that some tech journalists can still write material understandable by an average person."

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Intel's Anti-Overclocking Technology Explanined
Posted: 2003-04-10 by nigel
By: Nathan

Introduction

Many of you may have read the recent article in the inquirer that reports on a patent that was granted to Intel for an overclocking detection and prevention device. With all due respect to our fellow journalists (they did post the story first), this article was a little lacking on the clear technical interpretation that we know our readers crave. As an alternative, you could fight your way through "United States Patent 6,535,988 - March 18, 2003", but to save you the trouble we here at Fastsilicon.com have done it for you. Herein we present a layman's guide to the patent that has got some of the overclocking community up in arms, and tell you why it's all bad. To begin our explanation, it is appropriate to explain how the system clock relates to the processor, and what "overclocking" is all about.

Clocking, Over- and Otherwise:

The way processors work in conjunction with their clock is fairly simple. Connected to the microprocessor's core is a device that produces an electrical pulse a certain number of times per second. This pulse is a sort-of "heartbeat", and with each pulse the processor does some work. The faster the pulses come, the more work the processor does. The rate at which the pulses come is expressed in units of Hertz (abbreviated as "Hz"), which stands for "times per second". If our pulse is coming 1 time per second, then we say that it has a frequency of "1 Hz", and hence the processor speed is 1 Hz. Obviously nobody runs processors at this speed; we are more accustomed to processor speeds that are measured in Megahertz (MHz) or Gigahertz (GHz), where 1 MHz is 1 million times per second and 1 GHz is 1 billion times per second. Additionally, some processors internally multiply this pulse, so in effect the processor sees (for example) 10 pulses for every external clock pulse. For the sake of simplifying things though, we'll ignore this multiplyer and proceed with the assumption that things are happening at a 1:1 ratio.

Many may ask at this point, "If the processor does more work with higher clock speeds, why are there limitations on the clock speed - why can't one run a processor as fast as they want?". Although there are many factors that contribute to the answer to this question, the basic answer to this is heat. With every clock pulse, electricity flows through the processor. Because of resistance in the processor's pathways (think of it as a sort of electrical friction), some of this energy is converted to heat, similar to what happens when you rub your hands together very quickly. The higher the clock speed, the more often the clock pulses come, which means that more heat is generated at higher clock speeds. Because processors don't react well to the effects of this heat, testing is done to determine the maximum clock speed that they can run at safely. The processors are then labeled with this clock speed, and they go out the door with a designation such as, "Pentium 4 - 2.4GHz". In this particular case, Intel has tested the processor and has determined that to run properly, it needs a clock that runs no faster than 2.4 billion times per second.

Running a processor at a higher clock speed than labeled by increasing the rate at which clock pulses happen is known as "overclocking". Because there is some "statistical leeway" in the tests that are done to determine the maximum clock speed, many times one can overclock a processor and achieve more performance without a perceived negative effect. As most hobbyists know, these negative effects come somewhat gradually as you slide up the clock speed curve. At one clock speed things may be good, but as one increases it they see more system glitches until the computer simply will no longer boot. This is where the "perceived" part of the negative effect comes in. One may not outwardly notice errors as they use a moderately overclocked system, but they still may be occuring, and the life of the processor may be de