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Specialized CPU Coolers Lots of companies sell third-party heat sinks and fans for a variety of CPUs. These usually exceed the OEM heat sinks in the amount of heat they dissipate. These CPU coolers invariably come with eye-catching designs to look really cool inside your system—some are even lighted (see Figure 5-69).

Figure 5-69 Cool retail heat sink

The last choice is the most impressive of all: liquid cooling! That’s right, you can put a little liquid-cooling system right inside your PC case. Liquid cooling works by running some liquid—usually water—through a metal block that sits on top of your CPU, absorbing heat. The liquid gets heated by the block, runs out of the block and into something that cools the liquid, and is then pumped through the block again. Any liquid-cooling system consists of three main parts:

A hollow metal block that sits on the CPU

A pump to move the liquid around

Some device to cool the liquid

And of course, you need plenty of hosing to hook them all together. Figure 5-70 shows a typical liquid-cooled CPU.

Figure 5-70 Liquid-cooled CPU

A number of companies sell these liquid-cooling systems. Although they look impressive and certainly cool your CPU, unless you’re overclocking or want a quiet system, a good fan will more than suffice.

Whether you have a silent or noisy cooling system for your CPU, always remember to keep everything clean. Once a month or so, take a can of compressed air and clean dust off the fan or radiator. CPUs are very susceptible to heat; a poorly working fan can create all sorts of problems, such as system lockups, spontaneous reboots, and more.

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EXAM TIP CPUs are thermally sensitive devices—keep those fans clean!

Know Your CPUs

In this chapter, you have seen the basic components and functions of a PC’s CPU. A historical view has been provided to help you better understand the amazing evolution of CPUs in the more than 20-year life span of the personal computer.

The information in this chapter will be referred to again and again throughout the book. Take the time to memorize certain facts, such as the size of the various caches, CPU speeds, and clock-doubling features. Good technicians can spout off these facts without having to refer to a book.

Beyond A+

Overclocking

For the CPU to work, the motherboard speed, multiplier, and voltage must be set properly. In most modern systems, the motherboard uses the CPUID functions to set these options automatically. Some motherboards enable you to adjust these settings manually by moving a jumper, changing a CMOS setting, or using software; many enthusiasts deliberately change these settings to enhance performance.

Starting way back in the days of the Intel 80486 CPU, people intentionally ran their systems at clock speeds higher than the CPU was rated, a process called overclocking, and it worked. Well, sometimes the systems worked, and sometimes they didn’t. Intel and AMD have a reason for marking a CPU at a particular clock speed—that’s the highest speed they guarantee will work.

Before I say anything else, I must warn you that intentional overclocking of a CPU immediately voids any warranty. Overclocking has been known to destroy CPUs. Overclocking might make your system unstable and prone to lockups and reboots. I neither applaud nor decry the practice of overclocking. My goal here is simply to inform you of the practice. You make your own decisions.

CPU makers dislike overclocking. Why would you pay more for a faster processor when you can take a cheaper, slower CPU and just make it run faster? To that end, CPU makers, especially Intel, have gone to great lengths to discourage the practice. For example, both AMD and Intel now make all of their CPUs with locked multipliers and special overspeed electronics to deter the practice.

I don’t think Intel or AMD really care too much what end users do with their CPUs. You own it; you take the risks. A number of criminals, however,