09:14 AM

Tutorial: Build A Dual-Core System

Create low-cost, high-end PCs capable of running today's entertainment applications.

If you're looking to create a low-cost, high-end workstation or entertainment PC, it’s time to get up to snuff on dual-core processing technology.

The benefits of dual-core will be obvious to builders who love to multitask. With a dual-processor system installed, it means there’s a second processor core to share the load. For instance, if one processor is busy burning a DVD, the second is available to use for Web surfing or working on a PowerPoint presentation.

And while dual-core doesn’t mean your system’s chip itself is any faster, it does mean the capability exists for one chip to “talk” to another chip or device at a faster speed and with greater data throughput.

It may seem funny, but chip manufacturers such as AMD, Intel and Motorola are now touting their dual-core solutions at the same time many in the industry are wondering why the vendors hadn’t thought of it a long time ago. But let’s leave that debate to the “double-E's,” roll up our sleeves, look at what dual-core technology actually is, and examine how this technology will affect the construction of a white-box system.

Explaining Dual-Core Technology

Dual-core technology consists of placing two processors on a single die. That defines the manufacturing process, and it offers chip companies several advantages over single-core processor construction. First, manufacturers can build dual-core solutions without greatly increasing prices. Second, while dual-core processing doesn’t double performance, it does offer a significant performance increase. It also lets manufacturers scale back clock rates, reduce heat generation, and lower power requirements.

The secret lies in how the two independent processors communicate with each other. To understand that, you need to know about the underlying systems in a pipeline, cache and CPU.

Pipeline, as the name implies, is the avenue the processor uses to move instructions back and forth. The cache is the area on the die that can store the most frequently used instructions. Most dual-core processors share the pipeline, but each processor has its own cache. Pipeline sharing can help to further increase speed for applications that can leverage multiple processors, but unshared caching forces each processor to invalidate the other processors’ cache when accessing the memory controller. Another downside with a shared pipeline is that each processor must wait for the other to finish before starting its own tasks.

On traditional dual-processor systems, each CPU is treated as an independent unit with its own subsystems. With that in mind, it’s easy to see why true dual-processor systems can outperform dual-core based solutions, though at a significant increase in price. What’s more, some multiprocessor systems share a single memory controller, which can introduce inefficiencies.

But what system builders need to focus on is the application of the technology, not on whether a dual-core system should replace a traditional dual-processor system. The best way to decide that is to look at when dual-core solutions offer an advantage over single core technology. To discern that, hone in on how the processor will actually be used.

Can Windows Handle Dual Core?

The primary element to focus on is Symmetric Multi-Processing (SMP). That is where multiple processors can perform concurrent tasks. SMP capabilities are software-driven, which means applications must be SMP-aware to benefit from multiple-processor systems such as dual-core.

Herein lies the biggest obstacle, as many operating systems, such as Windows XP Home, are not SMP-capable and will not make use of the second physical processor. Also, most modern programs are single-threaded, meaning there’s only a single current set of linked instructions. As a result, only one processor can effectively work with those single-threaded applications.

So does this mean that the typical system builder should abandon dual-core processors? No! The key is to use dual-core based systems to build lower-cost, high-end workstations and entertainment PCs.

Why those particular systems? Because applications exist in those environments that can leverage SMP functionality. Graphics applications such as Photoshop, and CAD applications such as AutoCAD, thrive in multiprocessor environments. Also, OSes including Windows XP Professional can benefit from SMP-compatible systems, as well as Windows XP Media Center Edition. Finally, several high-end games can benefit from SMP, especially when it comes to rendering graphics and maintaining frame rates.

As they say, the proof of the pudding is in the eating. So let’s build a dual-core system and run some benchmarks to determine what improvements a system builder can expect.


To start this project, you'll first need to select the components that make the most sense. With a builder’s typical needs as a guideline, it’s apparent that a careful balance of cost and performance is required.

While both AMD and Intel offer dual-core offerings, product availability and established motherboard support drove me toward selecting an Intel-designed dual-core processor and Intel motherboard. That’s not to say Intel’s technology is superior to AMD’s, but as a simple fact of availability, it was easier for me to get my hands on Intel’s products.

Next, with an eye on economy, I selected the Intel Pentium D processor 820, Intel’s entry level dual-core processor. The D820 is a 2.80-GHz design, with an 800 MHz front-side bus and 2 MB of L2 cache. With a street price under $250, the D820 brings dual-core to the masses. Here's a look at this processor:

On the other end of the spectrum, system builders could select Intel’s top dog, the Pentium Extreme Edition 840, which runs at 3.2 GHz and offers hyper-threading. But you'll pay a lot more: The street price is around $1,000.

For a system board, I selected an Intel D945GNT motherboard, which is moderately priced at around $150 (street). It offers a host of features, including 1066/800 MHz FSB, DDR2 667/533, Intel 950 graphics, PCI Express X16, 4 PCI, 2 PCI Express X1, SATA (3.0Gb/s) RAID, IEEE-1394a, gigabit LAN, and high-definition audio. Here's a look:

For a case, I selected the Antec Sonata II, a mid-sized tower design that is geared toward quiet computing. This case offers front and rear panel ports, large low-speed fans, and a host of technologies to reduce noise. The case is also a “tool-less” design, using thumb screws for panel removal. The Sonata II is available in an attractive piano-black color for around $130, and it's worth every penny for those building media-style PCs. Here's a look at this case:

To finish out the components, I recommend the following three components...

...a BenQ optical drive:

...Kingston DDR-2 Ram (1 GB):

...and a Maxtor SATA drive:

Assembly and Installation

Assembling dual-core components is barely different then building a single-core system. Intel’s massive cooling fan for the CPU will need plenty of space for adequate airflow, but happily, the Sonata II case offers ducting that both provides sufficient fresh air for the CPU and helps keep the fan quiet.

After assembly, I booted the system from a Windows XP Pro disk and proceeded with installing the OS. The system's speed was evident, as the XP installation, along with SP2 installation, was accomplished rather quickly. After that, I installed the motherboard drivers and associated support files.

Now for the big question: how fast is the system? Well, speed is a subjective matter, but for an apples-to-apples comparison, I compared the dual-core system against an Intel Xtreme edition single core unit.

The results were surprising. The Extreme edition CPU outperformed the dual-core unit on every CPU statistic reviewed., as the following two charts show:

Keep in mind, however, that the Extreme edition costs significantly more than the D series. Further, while the Extreme edition has a cool name, many will prefer to have two processors instead of one. What’s more, when you consider the performance boost multithreaded applications will get from a dual-core system, the Extreme edition may not seem so fast after all.

What does all of this mean for the system builder? Simply put, dual-core CPUs offer a high level of performance for an economical price. That simple fact builds opportunity for the system builder by opening up new markets. Dual-core systems are a natural for the media-center market, for gaming systems, and as a low cost alternative for those looking for workstation-class systems. Dual-core proves to be a fun, effective way to get extreme performance at an affordable price.

CAROL ANN MUFF is the operations manager for Magnum Computer Consulting, a New York-based systems integrator specializing in custom accounting solutions for the small-business market.

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