Deciding which CPU will be the brains of your computer can be challenging, but you don't need to be a brain surgeon to do it. Here's what to look for when you compare processors.
By Matthew Murray
In the swiftly changing world of computers, few things stay constant for a shorter period of time than processors. Sure, technology changes drastically only every other year or so, but the names, capabilities, and benefits of any given CPU can be wildly different from month to month. Last year at this time, for example, we didn't have to worry about either Penryn or Phenom—let alone both of them together.
So when you're in the market for a processor, or even just a computer that uses one, there's serious potential for confusion. Do you want AMD or Intel? Does it matter? Is a quad-core CPU really better than just a dual-core model? And when you're looking at the spec listings for various processors, what do all the numbers mean?
Tracking down a processor doesn't have to be complicated. Once you know what you want and have a little bit of terminology under your belt, you can decode the dense language of clock speeds, caches, and cores to find the CPU that's just right for you—and your budget.
Balancing CPU and Graphics Card Performance
Whenever someone asks us what sort of hardware to buy, our first answer is always the same: What do you want to do with it? Your answer to that question affects your every purchasing decision. Processors are no different—the kinds of software you're most interested in running can (and should) influence your choice of CPU.
If you're having a hard time choosing between dual-core and quad-core, you might have another option. Though some apps, especially video editors and more demanding games, support multi-threading with more than two cores, a lot of software out there still doesn't get much of a boost from anything beyond two cores. So pairing a cheaper dual-core CPU with a good, discrete video card could net you more of a speed boost in many applications than would a quad-core CPU and a lower-end video card.
nVidia has established an "Optimized PC configurator" on its Web site to help you pair an Intel processor with select nVidia graphics cards to get the biggest performance increase. You might want to take the configurator's advice with a shaker of salt because, well, it's nVidia—and thus AMD's processors and powerful new ATI graphics cards aren't represented—but it's a good way to start thinking about what combination of components will best meet your needs.
CPU Overclocking
One good thing about a processor's clock speed is that you're not necessarily stuck with it. Many processors, especially those at the upper end of the spectrum (where hard-core gamers, performance freaks, and other bleeding-edgers live), allow you to squeeze even more performance from them by manually changing their settings (known as "overclocking"). You could change a 3GHz processor into a 4GHz one—without spending one extra penny.
This prospect is risky, though—if you make a mistake, you could experience crashes or even do serious damage to your system. Don't even think about heading down this road unless you're willing to take the chances and are well-versed in the mechanics of overclocking.
But if you're feeling adventurous, look for a CPU with an unlocked multiplier. The multiplier is the number that tells the processor how many times faster than the processor bus it should run. If there are no limits on that number, you have a lot more freedom to experiment in finding the proper speed—just make some adjustments to a few entries in your system BIOS, and you're set. It's also possible to overclock processors that have fixed multipliers, though in that case you'll need to increase the speed of the system bus, too—which comes with its own set of challenges. The amount of overclocking you can perform also depends on the motherboard you're using—not every model supports the process.
Whatever you do, remember that overclocking can put undue strain on your components, and you'll have to deal with the additional heat it produces. Make sure you're aware of the problems you'll face—and that you know how to work around them—before going above the safe-and-sound factory-set clock speeds. (For more information, check out our overclocking tutorial.)
