CPU Buyer's Guide

It's not quite as soul-wrenching as buying a new car, but it's close: Picking a CPU for your desktop PC(s) is a decision you'll be living with for years, so whether you're buying for yourself or for a company, it's important that you make the right choice the first time.

In recent years, the decision has become even more complex. AMD's success has doubled the number of choices you have to make, and that's just the beginning of the headache. Intel recently switched from a clock-speed-oriented naming convention to a model-number system similar to AMD's (and BMW's, but that's a whole other story). And this summer both chipmakers launched brand new lines of dual-core desktop CPUs that promise to improve multi-tasking desktop performance by leaps and bounds.

But do you really need leaps and bounds? As always, that depends on what kinds of tasks you and/or your users employ their desktop PCs for. Regardless, CPUs aren't cheap, so it's important you understand what your needs are before you execute.

To help you make this critical decision, we've put together a comprehensive buyer's guide to both Intel's and AMD's lineups. We'll explore all currently available processors in four different categories, from performance processors to the high-end, mid-range, and value categories. We have specs, prices, and pertinent performance information.

We also have a quick-hitting CPU Buyer's Q&A that will assist you in your decision-making process by answering critical questions about Intel's new naming convention, future considerations, and more.

Performance Processors

AMD Processors: Athlon 64 FX-57, Athlon 64 X2 4800+, Athlon 64 X2 4600+, Athlon 64 FX-55

Intel Processors: Pentium Extreme Edition 840, Pentium 4 670

Loaded with one megabyte or more of L2 cache and boasting extremely high clock speeds, these six CPUs are the Ferraris of the processor world: Practically no one needs them, but they sure are fun to drive. These CPUs offer such outrageous performance they merit a category all to themselves. At $1,000 a pop, they're not cheap, either. All CPUs in this category support 64-bit computing.

While no one would refuse such power, the only people who really need this level of performance are:

And that's it. The price delta between these CPUs and ones in the high-end category does not justify their purchase for anyone else.

Note: Intel's and AMD's CPUs run at different clock speeds. This does not indicate faster or slower performance.

Meet The CPUs

AMD FX-57: If you're looking for superior performance -- in games and otherwise -- AMD's FX-57 is the king of CPUs. Running at a clock speed of 2.8GHz, the top of the line for AMD's processors, this CPU features a massive L2 cache of one megabyte. In benchmarks, the FX-57 has posted superior performance numbers in almost every category that doesn't involve multi-tasking. One nice feature of the FX processors is that for the processing power they offer, they don't run at very high temperatures. That typically translates into increased stability. But at $1,016, they're definitely not cheap.

One other attribute of the FX-57 won't be a factor in most offices: It's easier to overclock than Intel's high-end processors, which means that serious techies will be able to squeeze some extra performance out of systems based on this CPU.

Intel Pentium Extreme Edition 840: Intel's answer to AMD's FX line is the intimidating Pentium Extreme Edition 840 processor. The 840 is a dual-core CPU, which means that it actually contains two processor cores in one CPU shell. Each core runs at 3.2GHz and features a one-megabyte L2 cache for increased performance; the presence of Hyper-Threading in each core allows Windows XP to recognize this CPU as a four-processor chip, which translates into high multi-tasking performance.

Because most games and applications have not been optimized for multi-tasking, AMD's FX-57 is faster in most single-application benchmarks. However, in a multi- or hyper-tasking environment, the 840 is an excellent choice.

This level of performance comes at a price -- a cool $1,100. And that's not including the new motherboard based on Intel's 955X chipset you'll need to support Intel's dual-core processors. But assuming that more and more applications and Windows Vista will be written to take advantage of dual-core processors, the 840 will probably be a more cost-efficient investment in an office environment than the FX-57.

AMD Athlon 64 X2 4800+ and Athlon 64 X2 4600+: AMD's Athlon 64 X2 4800+ and 4600+ dual-core processors also present superb performance, again in the astonishingly high price range of $900 to $1,100. Like Intel's Pentium D series, AMD's X2 line features two CPU cores in one housing, which allows for much faster multi-tasking. The 4800+'s cores run at 2.4GHz and have 1MB L2 caches, while the 4600+'s cores run at 2.8GHz and have 512K L2 caches.

It's worth noting that in benchmarking, Intel's Pentium Extreme Edition 840 appears to be slightly faster than the X2 4800+ in office-oriented productivity applications, while the 4800+ is slightly faster in most other categories. No Hyper-Threading here: both the 4800+ and the 4600+ lack the Pentium 840's ability to function as four CPUs in a Windows environment. 

The nice thing about the X2 4800+ and 4600+, however, is that they present an easy upgrade path. If you're already running Athlon CPUs on Socket 939, you don't have to buy a new motherboard to utilize these CPUs. Again, given the massive movement toward dual-core CPUs, it's highly likely that more and more applications as well as Windows Vista will be coded to take advantage of dual-core processors. That gives these CPUs extended longevity.

Intel Pentium 4 670: Formerly known as the Prescott Pentium 4, the 670 runs at a blistering hot (literally) 3.8GHz. Besides the fast clock speed, these CPUs feature a gargantuan two-megabyte L2 cache, which greatly aids performance in all applications, particularly gaming and video. The price tag for all this is close to $1,000.

It's worth noting that for a few hundred dollars less, you can get comparable single-thread performance with the high-end Pentium 4 660, 571, and 570J, which are detailed on the next page.

Athlon 64 FX-55: This is the same exact processor as the Athlon FX-57, except that the clock speed is only 2.6GHZ instead of 2.8GHz. The difference in performance isn't tremendous, and the price is only around $860, so if you're considering a performance CPU, the FX-55 is an excellent lower-cost alternative to the FX-57.

High-End Processors

AMD Processors: Athlon 64 X2 4400+, Athlon 64 X2 4200+, Athlon 64 4000+, Athlon 64 3800+, Athlon 64 3700+

Intel Processors: Pentium D 840, Pentium D 830, Pentium 4 660, Pentium 4 571, Pentium 4 570J

Sticking with our car analogy, high-end processors are like Porsche Cayennes or BMW M3s. They offer 80th- to 90th-percentile performance and advanced features at a high cost, but aren't outrageously expensive. Of course, notions of expense vary depending on your budget, but $450 to $700 beats $1,000 any day of the week.

When it comes to office productivity, time is money, so you should consider these processors for users who frequently juggle a large number of open applications, or who perform a considerable amount of multi-tasking and/or audio and video encoding. If Office XP is the most rigorous suite of applications you or your people will be using, the mid-range category of CPUs is probably a better economic decision. As always, however, the faster the processor, the longer it will satisfy the user.

In this category, we give the nod to dual-core processors over the single-core platforms. Following the lead of AMD and Intel, Microsoft and other software developers will probably begin to write application code that takes advantage of dual-core processing. This shift should give extended longevity to dual-core systems as early as next year. We'll know for sure toward the middle of next year.

Note: Intel's and AMD's CPUs run at different clock speeds. This does not indicate faster or slower performance.

Dual-Core

Intel Pentium D 840 and Pentium D 830: One of the constants in the ongoing battle between AMD and Intel has been that AMD has consistently offered everyday CPUs for lower prices than Intel. These circumstances changed dramatically this year when Intel debuted its dual-core Pentium D 840 and 830 processors for $600 and $450, respectively. Both are cheaper than similar-performing dual-cores from AMD.

Similar to their Pentium Extreme Edition 840 big brother, the Pentium D 840 and 830 feature two CPU cores within a single casing, each with 1MB of L2 cache and the ability to run 64-bit code. The key difference is that the Pentium D dual-core processors lack the Extreme Edition's Hyper-Threading capabilities, which allow Windows XP to recognize it as four processors instead of two. The 840 runs at a clock speed of 3.2GHz, while the 830 runs at 3.0GHz. Both are more than capable of giving a substantial boost to users who juggle one or more CPU-hungry applications such as video, audio, or 3D rendering at the same time.

AMD Athlon X2 4400+ and Athlon X2 4200+: AMD's responses to the Pentium D 840 and 830 are the Athlon X2 4400+ and 4200+ dual-core processors. Both run at 2.2GHz. In the 4400+, each CPU core has 1MB of L2 cache, while in the 4200+ each CPU core has 512KB of L2 cache. Higher amounts of L2 cache result in a significant performance increase, because programs can access data stored here faster than in standard memory. Not surprisingly, it adds to the overall cost of a CPU. Aside from this, the two CPUs are identical. Each permits 64-bit operations.

One key difference AMD likes to point out between Intel's dual-core CPUs and their own is that Intel's dual-core architecture does not allow the two CPUs to communicate efficiently. For the two CPUs to exchange data, they must send the data out to the front side bus and then back to the CPU core. AMD's approach is much more efficient; however, memory limitations in the architecture of the Athlon 64 X2 series also limit performance. At this point, most experts consider this a wash.

What isn't a wash, however, is price. The Athlon 64 4400+ costs around $650, while the 4200+ costs around $550.

Single-Core

While we recommend dual-core CPUs for most office environments, a number of single-core high-end processors are worth looking at for desktop PCs that see considerable use of a single, CPU-intensive application, such as gaming or audio/video encoding.

Intel Pentium 4 660, Pentium 4 571, and Pentium 4 570J: With 2MB of L2 cache and a 3.6GHz processor, Intel's Pentium 4 660 is similar in nature to the Pentium 4 670 detailed in the performance category. The slower clock speed makes it a slightly more affordable $700. That's still not cheap, but it's $300 less than the 670, which might make this a great processor for the few users in your office with extravagant CPU demands.

Similar to the 660 is the Pentium 4 571, which runs at a slightly faster 3.8GHz but features only 1MB of L2 cache. Because the 571 costs only $50 less than the 660, we're going to recommend the CPU with the larger cache. The resulting performance difference is well worth the $50. Intel also offers the Pentium 4 570J for around $650; it's exactly the same as the 571, but without 64-bit extensions. (Why you'd want to pay the same price for a processor with less functionality is beyond us.)

AMD Athlon 64 4000+, Athlon 64 3800+, and Athlon 64 3700+: AMD also has a handful of single-core high-end CPUs: the Athlon 64 4000+, 3800+, and 3700+. All three run at 2.4GHz. But while the 4000+ and the 3700+ feature 1MB of L2 cache, the 3800+ has only 512KB. One key difference between the 3700+ and the other two is that the 3700+ uses an older 754-pin CPU socket instead of the newer Socket 939. This will make upgrading more difficult in the future, particularly if you want to switch to AMD's dual-core processors, which also use Socket 939.

All three of these CPUs offer better performance per dollar than the Intel CPUs above. The 4000+ costs $550, the 3800+ costs $390, and the 3700+ will set you back $350.

As with many of the single-core AMD and Intel CPUs, AMD processors tend to exhibit faster performance in gaming, while Intel processors are faster at office productivity applications.

For standard office computing, the 3800+ represents the greatest value in terms of price and performance of all the single-core CPUs discussed above. The P4 660's performance is remarkable, but if you're going to spend almost $700 on a CPU, you might as well spend a few hundred dollars more and get a truly powerful CPU such as the Athlon 64 FX-55.

Mid-Range Processors

AMD Processors: Athlon 64 X2 3800+, Athlon 64 3500+, Athlon 64 3200+, Athlon 64 3000+

Intel Processors: Pentium D 820, Pentium 4 551, Pentium 4 541, Pentium 4 531, Pentium 4 521

Mid-range CPUs are like minivans in their utilitarian nature. This category of processors offers extremely affordable and satisfying levels of performance to users who need their PCs for basic computing tasks. If you or your workplace primarily uses Office XP and a few other non-CPU intensive applications, such as basic database operations and Web surfing, these processors will work well for you. Don't expect to be able to encode a CD or DVD while you quickly scour the Web or check your e-mail, however.

Note: Intel's and AMD's CPUs run at different clock speeds. This does not indicate faster or slower performance.

Dual-Core

Intel Pentium D 820: The shining star in this category is Intel's Pentium D 820. At $250, it's an extremely affordable dual-core solution that offers amazing multi-tasking performance for its price, as well as 64-bit support. The 820 runs at 2.8GHz, and each core features 1MB of L2 cache.

AMD Athlon 64 X2 3800+: For months, it appeared that AMD would completely abandon the mid-range dual-core CPU category to Intel and focus its efforts on higher-priced premium CPUs. However, the company recently released the Athlon 64 X2 3800+, a mid-range dual-core that offers premium performance at a much lower price than the X2 4200+. The X2 3800+ runs at a clock speed of 2.0 GHz, and each core features 512K of L2 cache.

While Intel's Pentium D 820 has twice as much secondary cache, early benchmarking tests have shown favorable results for the X2 3800+, particularly in gaming and multi-threaded application performance. That said, at $350 this CPU costs almost 50 percent more than the 820.

Single-Core

Intel Pentium 4 551, Pentium 4 541, Pentium 4 531, and Pentium 4 521: Intel offers a handful of other Pentium 4-based single-core CPUs in this category. The Pentium 4 551 runs at 3.4GHz, the P4 541 runs at 3.2GHz, the 531 runs at 3.0GHz, and the 521 runs at 2.8GHz. Each has 1MB of L2 cache, Hyper-Threading functionality, and 64-bit support. The prices range from $300 for the 551 to $180 for the 521.

AMD Athlon 64 3500+, Athlon 64 3200+, Athlon 64 3000+: AMD offers a bevy of single-core Athlon 64 processors in the mid-range. The Athlon 64 3500+ runs at 2.2GHz and features an L2 cache of 512KB. The 3200+ and 3000+ also have 512KB L2 caches and run at 2.0GHz and 1.8GHz, respectively. With larger L2 caches, Intel's mid-range Pentiums beat these CPUs in Windows office application performance, but they also cost slightly more. The 3500+ can be found for around $275, while the 3200+ and 3000+ cost only $210 and $150, respectively.

At this range, you get what you pay for -- which isn't much at the bottom end of this set of CPUs. Our recommendation: If you can afford it, go with either Intel's or AMD's dual-core offering.

Low-End Processors

AMD Processors: Sempron 3300+, 3100+, 3000+, 2800+, 2600+, 2500+, 2400+

Intel Processors: Celeron D 351, 346, 345J, 341, 336, 331, 326, 320, 315

Intel and AMD both have their own low-end or "value" classification of CPUs. These low-end CPUs are more like scooters than automobiles. They'll get you where you need to go, but they won't carry a heavy computing load or move very quickly. Drop a PC with one of these CPUs in it onto a professional's desk and you'll probably make someone mad.

That said, however, these processors can perform basic computing tasks such as Web browsing, e-mail, and other non-CPU-intensive applications with a minimal consumption of power, so you'll have lower energy bills. In addition to slower processor speeds, these CPUs tend to feature small L2 caches, which constrain performance. On the bright side, less L2 cache results in much lower prices. We're talking $100 or less for this class.

Note: Intel's and AMD's CPUs run at different clock speeds. This does not indicate faster or slower performance.

Intel Celeron D processors: Intel has named its low-end category Celeron D. The "D" does not refer to dual-core. The model numbers range from the Celeron D 351 ($240), which has a decent 3.2GHz clock speed but only 256KB of L2 cache, to the Celeron D 315 ($70), which runs at 2.26GHz and also has 256KB of L2 cache. Beyond the clock speed, the key constraint in the Celeron D line is the front side bus speed of only 533MHz, which seriously slows down data transfer rates.

AMD Sempron processors: AMD's value line is named the Sempron series, and ranges from the Sempron 3300+ ($160), which runs at 2.0GHz, to the 2400+ ($70), which runs at 1.67GHz. These processors also have only 256KB of L2 cache.

The Sempron processors use a little less power than Celeron processors. Given how slowly they run, the performance difference between the two lines is negligible.

CPU Buyer's Q&A

What difference does clock speed make if most of my users are using their systems for surfing, word processing, and the occasional spreadsheet?

Whether you're playing games or doing word processing, increased clock speeds almost always result in noticeably faster user experiences. This performance increase is less noticeable if you're typing a memo in Microsoft Word, but faster CPU speeds will certainly result in faster PC boot times, more rapid switching between Windows XP user accounts and applications, quicker load times for Web browsing, and faster downloading of e-mail. Whether these extra seconds will make a tremendous difference to your users is for you to decide.

If you're using CPU-intensive applications, such as audio and video encoding, or even 3D rendering, you'll notice a much more dramatic, time- and money-saving reduction in the time required for your PC to complete these tasks. Also, faster CPU clock speeds will allow you to perform multiple tasks faster, such as loading a Web page while you encode an audio CD. This can be a boon if you frequently use a large number of applications at the same time. Increasing main memory can also have a positive impact upon multi-tasking.

One final note: Intel and AMD CPUs each feature markedly different clock speeds. The fact that Intel's Pentium 4 processors run between 3.0 and 3.8GHz in no way indicates faster performance than AMD's 2.2GHz to 2.8GHz processors. They're based on completely different architectures.

Before I buy new desktop PCs, are there other upgrades I can make that will have a positive impact on performance?

Absolutely. If your CPU or CPUs fall into the mid-range category we've specified and you're running with only 256MB or 512MB of RAM in your systems, you should definitely consider an upgrade to 512MB or even 1GB. This will result in smoother, faster transitions between applications in Windows. 

​​​​​​​Is there any reason I should wait to buy new CPUs or new desktop PCs?

Not particularly. These days, both Intel and AMD are constantly launching new CPUs, which constantly drives down prices on previous models.

You can usually find great deals on performance or high-end processors when Intel and/or AMD release (not announce!) new models. As an example, when AMD released the brand new Athlon 64 FX-57, the price of the FX-55, which isn't too much slower, came down a few hundred bucks.

If you're wondering whether or not you should wait for Microsoft to release Windows Vista before you upgrade, the answer is a resounding no. While this new OS will likely require a more powerful system to run, it won't present any system or component requirements that instantly make the systems you buy today obsolete.

However, if you think you'll want to upgrade to Windows Vista when it does become available, you should plan your PC purchase accordingly. Make sure you buy CPUs in the high-end range (think dual-core), and you shouldn't see too big a performance hit when you upgrade to the new OS.

Should I be thinking about buying dual-core processors or desktop systems based on dual-core technology?

Definitely, particularly given the affordable prices of Intel's dual-core CPUs at the mid-range. At a little under $300, the Pentium D 820 series is a great bargain that will speed up basic computing tasks and be able to take advantage of the increased dual-core support at the OS and software application level that should begin to trickle into the desktop environment next year.

Unless you're a hardcore gamer, dual-core technology is worth your time and money. Even today, Windows will give significant performance benefits to power users who often have five or six different applications running at a time. 

​​​​​​​What about 64-bit processors? Should I make sure the CPUs I buy have 64-bit support?

This is pretty much a moot point, since all the processors in the performance, high-end, and mid-range categories have built-in support for 64-bit extensions. We're dubious whether or not this support will pay off at all until Windows Vista debuts, however. Unless you're using Windows XP 64-bit edition, you'll experience no noticeable performance increase from the presence of 64-bit extensions at the CPU level.

Is there an easy way to decipher Intel's new naming convention?

Yes, there is.

In an effort to make CPU decision-making easier, Intel switched to a brand new naming scheme earlier this year. Is the new format, which eschews all references to clock speed in favor of a naming hierarchy that is similar to the way BMW names its cars, easier to understand? Perhaps in time it will be, but it's certainly creating a great deal of confusion now. The model number sequence works as follows:
 

In general, the higher the family number, the more advanced and speedier the processor. The higher the model number within the family number (e.g., 840 as opposed to 820), the higher the clock speed, L2 cache, or front side bus speed -- but not necessarily all three. Intel calls this easier?

Quick Reference: CPU Specs

AMD and Intel don't list prices for their CPUs, so the prices on this page are averaged from the top online sellers as of August 2005. These prices are subject to change and will no doubt drop over time.

We've included the top specs on this page. You can find more detailed specifications for AMD's entire processor lineup on the AMD site and for Intel's entire processor lineup on the Intel site. Intel also has a printable and downloadable spec chart (PDF) that compares each CPU for handy reference.

Note: Intel's and AMD's CPUs run at different clock speeds. This does not indicate faster or slower performance.

Performance CPUs

High-End CPUs

Mid-Range CPUs

​​​​​​​Low-End CPUs