How to overclock your CPU

Why overclock?

Overclocking the system processor is one of the easiest tweaks you can do to get more performance out of your PC. Motherboard manufacturers have steadily opened up more voltage and clock-speed options within the system BIOS to give ambitious overclockers the tools they need to get the most out of their CPUs. Processor manufacturers, desperate to capture the gaming market, have also relaxed their anti-overclocking stance, as we've recently seen in awkward lunges aimed at the PC gamer: the "unlocked" Athlon 64 FX and the Intel Extreme Edition processors. The FX and Extreme Edition chips fill a need for extreme overclockers who are looking to create the fastest chip possible using any means necessary. But regular enthusiasts know that paying $1,000 for an unlocked chip violates the spirit of overclocking--the entire purpose of the act is to get an inexpensive processor running as fast as a ridiculously expensive one.
For this edition of Press Start, we'll get you familiar with the basics of overclocking and explain what kind of equipment you'll need to get started. This feature isn't a comprehensive guide, as there are entire Web sites devoted to the subject, but hopefully you'll learn enough to determine whether or not you'd like to give overclocking a try.

What you need

If you want to overclock effectively, you need a few choice components. You'll want to get a CPU that has lots of headroom, a large speed margin between its standard speed and the top speeds achieved by other processors that share the same basic microarchitecture design. You're also going to need a motherboard that gives you the necessary overclocking tools like CPU and northbridge voltage selection options. Then you might want to consider upgrading the CPU cooling, although that does add considerable expense and some CPUs have been known to be phenomenal overclockers using the stock fans and heatsinks.

The CPU model greatly affects what kind of overclock you can expect. Numerous Web sites and forums cover which processors are the most suitable for overclocking. For a good budget overclocking attempt, you want to stick to CPUs that cost less than $250. Sometimes, great bargains appear in the $150 range, but they don't come along too often. Among modern processors, the best bets for overclocking lie in the budget segments of Intel's new Core2 Duo and AMD's Athlon 64 X2 processors. Exact model numbers will vary as time goes on, but you usually want to go with the slower processor models since they're cheaper and provide more overclocking headroom.
Not all CPUs of the same model will overclock to the same levels. Some CPUs can run a little faster, while others can't. The more expensive processors have all been qualified to run at higher speeds, but the cheaper processors may have only graded out at lower speeds. When you buy a processor specifically for overclocking you're basically betting that the manufacturer's production quality is high enough that even the inexpensive chips can run at much faster speeds.
Pair up your CPU with memory suitable for the job. If you're going for a budget overclock, purchase only the speed you need. Low latency memory and high-speed memory cost a substantial amount and provide marginal gains in comparison to a large CPU overclock. If you're looking to squeeze out the most performance, regardless of budget, then premium memory is worth exploring. Buying faster memory "in preparation for the future" is pointless since you'll likely need a new a type of memory by the time you're ready to upgrade.

You will also need a motherboard that's willing to cooperate in the overclocking plan. Companies like Asus, DFI, MSI, Gigabyte, and Abit all manufacture motherboards specifically made for the tweaker. These motherboards feature extra options in the BIOS, more advanced cooling features, and better power-handling capabilities. Stay away from Intel brand boards and many name-brand pre-built systems if you plan on overclocking since they often don't have the BIOS settings that allow you to overclock the processor.
Extra cooling in the form of faster fans, better heat sinks, and water cooling (if you want to go exotic) all help to improve your chances of achieving a successful overclock. Some notable companies in the field of cooling include Thermaltake, Zalman, Alpha, and Thermalright among others, but lots of overclockers have had good success using the standard cooling units that come with the processor.

A good thermal paste, when correctly applied, is an absolute must-have especially if you're sticking with the stock heatsink and fan. There's no shortage of companies pedaling a cornucopia of metallic slimes: Arctic Silver, OCZ, Masscool, Antec, Kingwin, Cooler Master, and Artic Cooling. The key to unlocking the benefits of thermal compounds involves how you apply them. Make sure to place an even and very thin layer over the CPU. If you have too much paste on the CPU, the compound actually inhibits the transfer of heat to the heatsink.

Twice the speed for half the money >> »

Are you an experienced veteran with several processors under your belt? What CPU do you have and how high have you overclocked it?