Dual-Core CPU Buyer's Guide

AMD refreshed Intel introduced "Core" microarchitecture

"Now is a great time to buy," said Chris Walker, Intel's director of desktop CPU marketing. Sure, Walker's got some skin in that game -- Intel is intent on a successful launch for its new Core 2 Duo lineup. But from a consumer perspective, he's correct. The Core 2 Duo introduction touched off a price war between Intel and AMD. The upshot is that the latest chips from both vendors are far less expensive than they were only a short time ago, and many older dual-core processors are available for what amount to bargain prices.

In terms of the technology, both Intel and AMD have made significant strides since our last CPU buyer's guide, published in August 2005. Intel has updated the venerable NetBurst architecture used in its Pentium processor family with Core and Core 2 Duo. AMD has introduced its new AM2 socket, which effectively doubles the processor-to-memory bandwidth by adding support for DDR2 RAM.

To give you the information you need to make an informed decision, we've corralled all the processor specs into a comprehensive buyer's guide. As in last year's guide, we've covered both the Intel and the AMD lineups. Our emphasis is on dual-core -- soon, pretty much everything will be dual-core. Indeed, Intel expects to ship 10 million of its new dual-core chips within the next few months.

However, we're also listing a complete crop of single-core chips. Before you pooh-pooh such CPUs, remember that they offer the biggest bargains going if your PC usage steers away from gaming and multimedia in favor of everyday computing tasks such as e-mail and Web browsing.

For easier reading, we've separated the processors into four categories: performance dual-core CPUs, mainstream dual-cores, "bargain" dual-cores, and single-core CPUs. Along with descriptions of the chips, we bring you specs and the prices you can expect to pay in handy quick-reference charts. Performance Dual-Core Processors

AMD Processors: Athlon 64 FX-62, Athlon 64 X2 5000+
Intel Processors: Core 2 Extreme X6800, Core 2 Duo E6700, E6600, E6400, E6300

The conventional wisdom is that cutting-edge processors are largely for "enthusiast" users such as gamers, who demand the utmost in raw, uncompromised performance from their PCs. More recently, multimedia has been added to that mix. If you're editing movies and music, or simply using your system to watch a bunch of video streams, the fastest processors will enable your applications to avoid those annoying, unintentional pauses that are sometimes a prelude to a lock-up.

Despite the ongoing processor price war, when it comes to the ne plus ultra of dual-core performance, you're going to pay a fairly outrageous price. We're talking north of $1,000 for the top Intel offering and around $900 for AMD's best.

Only you can decide whether the bragging rights of owning one of these chips is worth its high price. It's always nice to have the best. On the other hand, remember that there's a much wider array of dual-core choices now available than was the case last year. Now, the combination of Intel's slew of recent introductions and price cuts on slightly older but by no means obsolete processors means that, this year, you can get some pretty good mainstream dual-core CPUs without paying through the nose.

Still, the best dual-cores money can buy are indeed good. Intel's Core 2 Duo processors, introduced in July, are widely considered to be the best-performing desktop CPUs around. They've won rave reviews from the likes of Tom's Hardware and TweakTown.

Not that AMD, which has as its top offering the Athlon 64 FX-62, has anything to apologize for. That CPU earned widespread kudos after it came out in May, and was, until Core 2, the top desktop chip.

Meet The CPUs

Intel Core 2 Extreme X6800: Because Intel and AMD continually one-up each other, no single chip can lay claim to being CPU performance king for very long. Nevertheless, right now, the new Core 2 Extreme X6800 can confidently be said to reside at the top of the heap. (Here's a list of recent reviews.)

For hobbyists intent on pushing their home-brew PC to the limit, the X6800 appears to be more amenable than most CPUs to overclocking -- the technique through which users push a chip well past its manufacturer's quoted clock speed. (The 2.93-GHz X6800 has reportedly been clocked as high as 3.75 GHz.)

At a street price of $1,100, it's not cheap. (Intel's list price for the X6800 in high-quantity "trays" sold to OEMs is $999.) There were also availability concerns following its introduction in late July, with some anxious gamers complaining they couldn't get systems. However, with Intel promising that the Core 2 family will have its fastest ramp-up ever, those concerns are abating.

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AMD Athlon 64 FX-62: AMD's top-of-the-line dual-core offering, the Athlon 64 FX-62, is no slouch either. It was king of the performance hill until the Core 2 Extreme came along, and it's still a worthy processor. Like all Athlon 64s, the 2.8-GHz, dual-core chip features an integrated memory controller. Putting the controller alongside the two CPUs, rather than in a separate area of silicon, enables faster memory access since data doesn't have to traverse a traditional front-side bus.

The FX-62 ushers in AMD's new AM2 socket, which upgrades the integrated memory controller to work with faster DDR2 RAM. The socket also brings support for AMD's virtualization technology to the desktop.

For home-brew experts who aren't content with the stock chip, it can be overclocked to 3.1 GHz. Best of all, the processor can be snapped up for around $900.

If you covet an FX-62 but can't quite come up with the cash, the 2.6-GHz FX-60 might be the way to go. It's officially an "end-of-life" part, meaning AMD is no longer making it, but many retailers still have stock on hand. It currently retails for around $600.

Intel Core 2 Duo E6700, E6600, E6400, E6300: Here's where setting the performance line among dual-cores gets tricky. After you factor price into the equation, it gets more difficult still. True, all four of Intel's Core 2 Duo "E" CPUs are slower than the Extreme X6800. However, the E6700, at 2.66 GHz, is only 9 percent slower than the X6800. Yet it sells for a street price of around $570 -- only a little more than half the price of its higher-end cousin. That's clearly a solid price/performance value proposition.

The pokiest of the four, the 1.86-GHz E6300, is 37 percent slower than the top of the line, but at a street price of a scant $196, it's approximately a third the cost of the E6700.

As for additional positives, all four of the Core 2 Duo "E" processors have the same fast front-side bus as the X6800 and all are amenable to overclocking as well.

AMD Athlon 64 X2 5000+: Is the phrase "high-end bargain" an oxymoron? If it's not, the Athlon 64 X2 5000+, introduced in May alongside the FX-62, might just fit the bill. The second-place processor in AMD's lineup is plenty fast: It's clocked at 2.6 GHz and has a dual, 1MB L2 cache. Like the FX-62, it uses the new AM2 socket, which supports fast, DDR2 memory.

As is the case with all of AMD's dual-cores, the 5000+ uses the company's HyperTransport interconnect to communicate between the processor cores and I/O subsystems. The bus is clocked at 2000 MHz, and in peak operation HyperTransport can deliver up to 8.0 GB/sec of total system bandwidth.

The 5000+ is very popular right now, and in incredibly short supply. That's both because it's intrinsically a great chip and because it's seen as a good alternative to the Core 2 Duos. Those two reasons have pushed up the street price of the 5000+ beyond the $301 list price set by AMD to as much as $325 -- still not a lot to pay. That price is even more impressive when one considers that AMD's top X2 model last year -- the Athlon 64 X2 4800+ -- was slower at 2.4 GHz, didn't support DDR2 memory, and sold for a whopping $1,100.

I used the 5000+ in my recent "Build A Dual-Core PC" project. Subjectively speaking, it's extremely fast. (That's not just my opinion -- my multimedia-savvy teenage daughter concurs.)

On the downside, although it has a thermal rating of 89W (compared to 125W for the FX-62), it seems to runs hotter than I had hoped. AMD's Cool'n'Quiet driver is available to downshift power usage when the extra juice isn't needed.

If you're in the market for a high-end dual-core, it's also worth keeping in mind that AMD is planning to freshen its X2 line before the end of the year. An Athlon 64 X2 5200+ is in the works. It'll have the same 2.6-GHz clock speed as the 5000+, but will double its L2 cache complement from 2 x 512KB to 2 x 1MB. Mainstream Dual-Core Processors

AMD Processors: Athlon 64 X2 4600+, Athlon 64 X2 4200+
Intel Processors: Pentium Extreme Edition 965, Pentium Extreme Edition 955, Pentium D 960, 950, 945, 920, 915

The difficulties in setting clear boundaries among dual-core processors become even tougher when you get to the "squishy middle" of the performance landscape. That's where the CPUs don't have the heft of the Core 2 Extreme or the FX-62, but aren't the clear bargain-basement parts you get with older, first-generation chips.

Accordingly, I've christened these devices "mainstream dual-cores." These include the meaty middle of AMD's Athlon 64 X2 line and Intel's Pentium 9XX series. The latter, also known as the Core Duo line, was Intel's top dual-core family before the new Core 2 Duos came along.

While these processors won't satisfy uber-geeky gamers, they will perform sufficiently for the vast majority of users. We're talking people who run office productivity applications along with the heavy Web surfing that's become pretty much the norm, encompassing everything from MySpace social-networking to YouTube video-viewing. I categorize such usage as heavier than the so-called "everyday" basic computing, which can be handled by cheaper, low-end dual-core and single-core processors.

Most important, the mainstream dual-cores run more than sufficiently fast to enable you to upgrade your PC to Microsoft's Windows Vista operating system, without any hiccups, when that OS comes along next year.

Meet The CPUs

Intel Pentium Extreme Edition 965 and Pentium Extreme Edition 955: Like an academically advanced child who's overshadowed by a sports-star sibling, these two processors have gotten short shrift in the hubbub surrounding the Core 2 Duos. Both "Extreme" CPUs are members of Intel's 9XX family. However, they were introduced less than six months before the Core 2 Duos, so they didn't get much time to shine.

Their main negative is that they use Intel's original "bolted together" dual-core design. This places two separate single-core CPUs next to each other on a single silicon die. It's far less elegant than the from-the-ground-up dual-core architecture used in the Core 2 Duos. Neverthless, the 965 and 955 are solid performers. More important, now that they're effectively obsolete, you can get good deals (see price chart).

The Extreme Edition processors are based on the longtime NetBurst architecture used in most Pentiums. However, they add support for Intel's Hyper-Threading and hardware-assisted Virtualization technologies. The former makes it easy to run multiple threads, which means better multitasking performance. The latter, which was largely unsupported in Intel's first dual-core chips, lets users run whole operating systems and apps in separate partitions, turning one physical CPU into a couple of virtual processors.

However, it's important to note that while many users will take advantage of Hyper-Threading, they're unlikely to do much with Virtualization because it's not widely utilized by desktop operating systems.

Both the 965 and 955 are made using Intel's advanced 65-nm semiconductor fabrication process, upgrading them from the 90 nm used for the earlier 8XX line and putting them on par in that regard with the Core 2 Duos.

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Intel Pentium D 960, 950, 945, 920, 915: There's little to say about the rest of the Pentium D 9XX line that doesn't already apply to the Extreme Edition 966 and 955. The family is filled out with five SKUs ranging in clock speed from 2.8 GHz to 3.6 GHz.

All support HyperThreading and Intel's Virtualization technology. The decision to go with a 9XX will rely largely on price. Unfortunately, the prices of the 9XX series are caught in a something of a pincer. Beneath them are the 8XX chips: not as good, but a heck of a lot cheaper. Accordingly, if you're really budget-constrained, you'd probably be better off looking at, say, the 805.

Above the 9XX in terms of performance is the new Core 2 Duo line. The two entry members of that family -- the E6300 and E6400, at around $196 and $243, respectively -- may be wiser choices, since they're not much more expensive than the 945, 950, and 960 cousins (see price chart). The 2.8-GHz 915, at $146, is a good compromise, combining mainstream dual-core performance with accessible pricing.

In a bid to pare down its huge array of dual-core SKUs, Intel in mid-August issued a notice that it would stop selling the 3.0-GHz Pentium D 930 and the 3.2-GHz 940 by the end of the year. Those processors are still available at the time this article is being posted -- both the 930 and 940 can be obtained from online retailers for around $200 and $210, respectively. However, for that money, you'd do just as well buying an entry-level Core 2 Duo.

One last factor to consider in your choice of processor is the cost of the motherboard you're planning to plug it into. While both the Core 2 Duo and the 9XX parts use the same Intel 775 socket, the Core 2 Duos require a motherboard equipped with the proper Intel core-logic chipset and updated firmware. While a 9XX motherboard can be had for around $100, figure you'll pay around $250 for one able to handle the newer processors.

AMD Athlon 64 X2 4600+ and 4200+: These two CPUs highlight the ongoing shift in the dual-core landscape. Last year, the 4600+ was included in our highest category -- performance processors -- among several other thousand-dollar chips. The 4200+ was listed as a high-end offering. Today, the 2.4-GHz 4600+ and 2.2-GHz 4200+ remain as solid as ever, but now they fall firmly in the middle of the dual-core pack.

But, boy, are these chips cheaper now. The X2 4200+ is available for $199, the 4600+ for $256. As David Schwarzbach, AMD's desktop product manager, puts it: "With the new pricing, we now have proven dual-core performance at affordable prices that are within reach of a larger portion of the market."

One other difference to note is that this year the two chips are being made in versions for the newer AM2 socket, which supports DDR2 memory. Older versions for the 939 socket have been "end-of-lifed" by AMD. Bargain Dual-Core Processors

AMD Processors: Athlon 64 X2 3800+
Intel Processors: Pentium D 805, 820

Our final dual-core category is something of an accident of history. Because Intel recently introduced its third generation of dual-core processors with the Core 2 Duos, but is still making some first-generation 8XX-series parts, the latter are now dirt cheap.

As for AMD, its low-end dual-core isn't outmoded technologically, but it's positioned as an entry-level offering and priced accordingly. If you want to run Vista on a dual-core -- and that's something you'd be strongly advised to do -- you can't get into the market any cheaper than with one of these CPUs.

Intel Pentium D 805, 820: True, the 2.66-GHz 805 and 2.8-GHz 820 are fabricated in Intel's older, 90-nm process technology and have smaller L2 caches than their 9XX cousins (2 x 1MB versus 2 x 2MB). Other than that, however, there's no significant difference. Though the more advanced 65-nm process used with the 9XX would lead one to assume that they're better on power consumption, the 805 and 820 do okay on that score, with a 95W thermal design power spec. Yet, at street prices of $93 and $120, respectively, they're the cheapest dual-cores around.

AMD Athlon 64 X2 3800+: The 3800+ boasts the same 2000-MHz HyperTransport bus as its higher-end 5000+ sibling. With a 2.0-GHz clock and 2 x 512KB L2 cache, it's also got nothing to be ashamed of, spec-wise. However, at $162, it doesn't quite bring up the bargain-priced rear of the market the way the low-end Intel 805 and 820 do. Single-Core Processors

AMD Processors: Athlon 64 3800+, 3500+, 3200+; Sempron 3600+, 3500+, 3400+, 3200+, 3000+
Intel Processors: Pentium 4 670, 661, 660, 651, 641, 631, 524, 521; Celeron D 356, 355, 352, 351, 350, 346, 345, 341, 340, 331, 326

When it comes to single-core CPUs, there's an embarrassment of choices. Accordingly, buyers should choose carefully. Intel and AMD say that their better single-core processors will do just fine with Windows Vista. However, I strongly recommend that prospective Vista users seek out a dual-core device. On the other hand, if your computing needs are mainly limited to so-called "everyday" tasks such as e-mail and Web browsing, and if you're budget-constrained, a single-core processor is a viable option.

Because financial considerations are likely to loom large among single-core buyers, I've divided the single core processors into two groups: faster single-cores and low-end processors. The former includes the Intel Pentium 4 6XX and Pentium 4 5XX series, and AMD's Athlon 64 family. The latter comprises Intel's Celeron Ds and AMD's Semprons. I really would prefer to call the two groups "orphans" and "dirt-cheap CPUs," but that might made certain vendors unhappy.

Unfortunately, "orphans" is an apt term for many members of Intel's 6XX series. Take the single-core, 3.6-GHz Pentium 4 660, which was a listed as a high-end processor in last year's buyer's guide. However, selling at $401 today, it's largely a relic, since you can get a dual-core CPU for a lot less money. That may be why some of the higher-end single-core SKUs seem either to be in short supply or aren't promoted much by boxed-processor retailers. One might also venture a guess that Intel will eventually winnow some of these processors from its product line, as it did recently with some of its superfluous dual-core models.

With dual-core rapidly maturing, the real remaining attractions among the single-cores are those best suited for everyday PC use. That's where the "dirt-cheap" CPUs come in. It's hard to argue with paying $31 for a 2.53-GHz Celeron D 326. That's a good way to go if you're buying a PC for a high-school student, new-to-computing parent, or dyed-in-the-wool business user who's unlikely to venture into funky new multimedia applications.

Faster Single-Cores

Intel Pentium 4 670, 661, 660, 651, 641, 631, 524, 521: Once Intel's flagship line, the Pentium 4 6XX family still delivers solid performance, ranging from a 3.8-GHz clock and 2MB L2 cache for the 670 down to a not-unimpressive 3.0 GHz with the same beefy cache for the 631. However, the 631 goes for around $176 at online retailers and the 670 -- if you can find it -- is a stratospheric $605.

The 5XX series preceded the 6XX, and is fabricated using older 90-nm technology. These processors are rapidly fading from the scene. Still shipped as boxed (retail) processors are the 2.8-GHz 521 and the 3.06-GHz 524. The 524 is generally available for $140; the 521 is harder to find. Some vendors still have residual stock of the 517, which exists only as an OEM part and is street-priced at $125. Again, I suggest you avoid these models in favor of a dual-core processor.

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AMD Athlon 64 3800+, 3500+, 3200+: Note that these models aren't Athlon 64 X2s -- "X2" denotes dual-core. These are plain-old single-core Athlon 64 designs, which were among the first desktop processors to implement AMD's groundbreaking 64-bit architecture.

The single-core Athlon 64s make a bit more sense price-wise than some of their Pentium 4 6XX competition. Perhaps that's because the scrappy semiconductor competitor fields fewer processors overall than Intel. A 2.0-GHz Athlon 64 3200+ lists for only $81. The top-of-the-line 2.4-GHz 3800+ sells for $120.

Low-End Single-Cores

Intel Celeron D 356, 355, 352, 351, 350, 346, 345, 341, 340, 331, 326: Here's a nomenclature no-no to remember: The "D" after "Celeron" does not put these parts in the same class as the Pentium D. These Celerons are low-end, single-core processors -- not dual-core devices. Note also that this family is divided up between Intel's Socket 775 and its rather aged Intel 478 socket. If you have the right motherboard, it doesn't much matter which one you get, since both types use a rather slow 533-MHz front-side bus.

The Celeron D 340, 345, and 350 use the 478 socket. The three CPUs also don't support Intel's 64-bit EM64T instruction set extensions. The Celeron D 326, 331, 341, 346, 351, 352, 355, and 356 are all socket 775 and do support EM64T.

If you're insistent on going single-core, and if your computing needs really are limited to everyday tasks, probably nothing fits the bill better than this family. Along with the aforementioned 2.53-GHz Celeron D 326 going for a scant $31, you can get a 2.93-GHz 340 for $40 or a 3.2-Ghz 350 for around $50. My suggestion, though, is to stick with the two most modern members of the family: the 3.2-GHz 352 and 3.33-GHz 356. Those two are the only Celeron Ds that have the added advantage of being 65-nm parts; the others use the older 90-nm process. They can be purchased for $69 and $74, respectively.

AMD Sempron 3600+, 3500+, 3400+, 3200+, 3000+: What is it with low-end processor names? "Celeron" sounds too close to "celery" for my taste. And "Sempron," which seems to have been chosen to connote the Marine slogan semper fi(always faithful), instead makes me think "simp," for simple. Which, like their Celeron competitors, they essentially are.

Like the Celerons, the Semprons come in versions spread among two different sockets: AMD's older 754 or its new, DDR2-supporting AM2. The Semprons also boast a faster system bus and use less power than the Celerons; however, most of the Semprons cost slightly more. The least expensive is the 3000+ at $61. (That chip runs at 1.8 GHz in its Socket 754 version, 1.6 GHz in AM2.) The family tops out with the $110, 2.0-GHz Sempron 3600+. Quick Reference: CPU Specs and Prices

Amid the slew of recent dual-core introductions as well as intense competition between AMD and Intel, prices for many processors are changing more frequently than in years past. Prices of older models -- both dual- and single-core -- are dropping. However, some of the newest Intel parts are in tight supply and command more than the manufacturer's list price.

Accordingly, the prices on this page are our subjective assessment, drawn from the vendor's list price and the street prices of the top online sellers, of what you're likely to pay for a processor in a single-quantity purchase as of September 1, 2006. These prices are subject to change and will likely drop over time.

We've also included the top specs on this page. You can find more detailed specifications for the companies' entire processor lineups on the AMD site and the Intel site, respectively.

Performance Dual-Cores | Mainstream Dual-Cores | Bargain Dual-Cores
High-End Single-Cores | Value-Priced Single-Cores

2. All of AMD's current processors are fabricated using 90-nm process technology. A 65-nm process is being readied at the company's new Dresden facility.

Performance Dual-Core CPUs

AMD Processors

* The new AM2 socket enables support for AMD Virtualization Technology.

** The X2 5200+ is due in Q4 of 2006.

Intel Processors

* Intel Virtualization Technology support ** Fabrication Process

Mainstream Dual-Core CPUs

AMD Processors

* The new AM2 socket enables support for AMD Virtualization Technology.

Intel Processors

* Intel Virtualization Technology support ** Fabrication Process

Bargain Dual-Core CPUs

AMD Processors

* The AM2 socket enables support for AMD Virtualization Technology.

Intel Processors

* Intel Virtualization Technology support ** Fabrication Process

(Specs and Prices, continued)

(Specs and Prices, continued)

Performance Dual-Cores | Mainstream Dual-Cores | Bargain Dual-Cores
High-End Single-Cores | Value-Priced Single-Cores

High-End Single-Core CPUs

AMD Processors

* The AM2 socket enables support for AMD Virtualization Technology.

Intel Processors

* The 6XX and 5XX series do not support Intel's hardware-based Virtualization technology; they do include Hyper-Threading. ** Fabrication Process

Value-Priced Single-Core CPUs

AMD Processors

* The AM2 socket enables support for AMD Virtualization Technology.

Intel Processors

* Celerons support neither Intel's hardware-based Virtualization technology nor Hyper-Threading. ** Fabrication Process