In “What you need to build your PC, part 1: The power supply and the motherboard,” I discussed two of the six main areas of the PC: the power supply and the motherboard. This time, I’ll take a look at two more pieces: the central processing unit and the hard drive. Find out how your choice of parts can affect the performance of a system.

The perplexing processor
When it comes to the ever-important processor, there are certain phrases that always come to mind: bigger is better, more power, and too expensive. Of course, if you want the newest and most powerful processor, you must be ready to pay accordingly. In many ways, the processor often becomes the primary focus of many people when they’re purchasing a PC. The real question is: Do you really need the newest and most powerful processor? As the war between AMD and Intel heats up, it looks like we’re going to enter the gigahertz realm very soon. But don’t overlook chips that are out there right now; they’re not too shabby. In most cases, users can’t tell the difference between a Pentium II and a Pentium III when they’re running the most common software suites.

Choosing a processor is where the research can become grueling. A lot of information is out there. The AMD K6-2 processor exists in many proprietary machines, and the Athlon has been breaking new ground. The Athlon even came out ahead of Intel in some bench tests. Intel has been experiencing great success with its Celeron processor, however, and you’ll find it in many of the proprietary machines on the market. Of course, the Pentium III processor has moved forward, and it’s prepared to pass the 800-MHz boundary very soon. You can choose from a huge selection of processors that are available, and there are reasons why you would want to choose one processor over another. Your choice depends on what you want to do with your PC and how much you’re willing to spend.

When looking for the right CPU, you must consider the bus (or clock) speed of the chip. The easiest way to measure the bus speed is by how quickly the CPU transfers data through its connection to the motherboard and then out to applications and devices. Bus speeds range from a slow 50 MHz to a fast 133 MHz. Currently, the most common speed is 100 MHz, which most motherboards support. The 133-MHz bus speed is fairly new, and you must make sure that you purchase a motherboard that will support the clock speed of your CPU. You also need to purchase memory that uses the same—or a higher—bus speed as the CPU. I’ll discuss this issue in greater detail when I cover memory in the next part of this series.

In many cases, the purchase of the CPU turns into a budget consideration. As one of the more expensive parts of the PC, it must achieve a balance between how much you want to spend and what you need to get out of the PC. One good thing about CPUs is that, as long as the motherboard supports them, they’re relatively easy to upgrade to newer models—an important factor for users with limited budgets.

Don’t get caught up in “the bigger the number, the better the processor” game. A good machine is made up of many good parts, not just a processor. You can purchase the biggest processor that’s available, but if the motherboard is not up to par and the power supply doesn’t regulate the current properly, your system still won’t perform well.

The hardy hard drive
As with all aspects of our daily lives, we need places to store stuff. For the PC, this place is the hard drive. Hard drives can become the greatest strength or the worst weakness of a PC. The performance of the hard drive that you choose will have a direct impact on the overall performance of your system.

Hard disk drives (HDD) are similar to the 3.25-inch floppy disks that you use. Hard drives contain disks (or platters) that are similar to the thin disk in a floppy. Other than the size, the main difference is that the floppy is made out of thin, flexible plastic, while a hard drive platter usually is made out of ceramic or glass that’s bonded with a thin magnetic coating. The magnetic coating is covered with a protective coating. (This coating is why hard drives are categorized under magnetic media and why you should exercise the same precautions around strong magnetic objects that you do around floppy disks.) In a hard drive, several of these platters are stacked together to form a cylinder that takes up most of the internal volume of the drive. The platters must be made with very tight tolerances and have a very smooth surface so that they can sustain the friction that’s created when they spin at a high rate of speed.

Just above the platter surfaces (10 microns above, to be exact) ride small read/write heads. Like fingers, the read/write heads extend into the narrow space that separates each of the platters in the stack. On a very thin layer of air, the heads are able to cover the width of the disk surface within milliseconds. As the heads move across the disk surface, they pick up the flux changes that are registered on the disk surface. These flux changes represent your data; when the CPU reads and processes them, the results will appear on your screen.

The most common drives today are based on Integrated Drive Electronics (IDE). This format places the hard drive controller within the drive itself, which makes it much easier for almost any firmware to use the drives. You’ll also see such terms as Enhanced IDE and Fast-ATA—all of which refer to certain drives. These terms just reflect the evolution of the IDE standard, and the drives will work with the IDE connections of a motherboard.

DMA drives
The big development in hard drives today is the Ultra DMA/33 (Ultra ATA/33) and the new Ultra DMA/66 (Ultra ATA/66) drives. These designations refer to the data transfer rates between drives and their controllers. (DMA stands for direct memory access.) The Ultra DMA/33 hard drives are capable of transfer rates of 33 MB per second; you can get transfer rates of 66 MB per second with the DMA/66 drives. However, the DMA/66 drives must meet certain requirements in order to get this high rate of transfer. For example, the ribbon cable for the DMA/66 is special. Although the DMA/66 has the same ends as the 40-pin interface connector that’s used on all other drives, it actually uses an 80-conductor ribbon cable instead of the standard 40-conductor cable. This special cable is usually included with the full retail box versions of the drives, but it may not be included in the white box version. You won’t achieve the DMA/66 transfer rates without this special cable. It’s possible to use the standard cable, and the drives are backward compatible to the DMA/33. But this method will limit the transfer rate. Furthermore, your motherboard or an expansion card must support DMA/66. The BIOS that your motherboard uses must support DMA/66, and the operating system that you choose must support direct memory access. DMA allows the drive to transfer its data directly into memory, bypassing the CPU entirely. If you can get everything together, you’ll gain some amazing speed with your system, but you won’t spend a great deal of money.

You’ll also want to consider the RPM speed of the drive that you use. Right now, the most common speed is 5200 RPM. Recently, some new drives came out with speeds of 7200 RPM. A faster spinning drive helps in the latency aspects. (Latency refers to the amount of time it takes for the read/write heads to reach the portion of the disk that contains the data they’ve been called to access. A faster spinning drive reduces this amount of time and speeds the transfer of data.)

In the PC world, size really does matter. Only a decade ago, a 500-MB hard drive was considered a very large drive. Now, we have hard drives that are 20 times that size, and that’s just on average. So, what size should you get? Buy the biggest drive that will meet your needs. Obviously, this item can eat up a large portion of your budget, but look at it this way: You’ll eventually run out of room. Unless you plan on purchasing some other drive that will let you archive files on a regular basis (such as tape or CD-writer), get the biggest drive that you can afford. The trend of new applications is to use more and more space on your hard drive. And you’d be surprised how quickly that space gets used up with just a few of these applications.

SCSI drives
For those of you who are considering the high-end workstation or server side of building a PC, you also should consider using Small Computer System Interface (SCSI) drives. Using SCSI drives and their interfaces adds the benefit of handling several devices on one connection. If total volume in drive space is what you need, then SCSI is your answer. By “daisy chaining” devices, you can reach up to 16 drives on one connection.

You’ll have a wide assortment of connections for SCSI devices from which you can choose. As SCSI has developed over the years, so have the connection types. After the SCSI-1 interface became standard and its 50-pin connector was adopted as the SCSI connection, a new Wide SCSI came out. It used a 68-pin connection.

There are two basic ways of integrating SCSI connections: Either the SCSI connection is built-in, or you’ll have to purchase a SCSI adapter board that will fit into one of your motherboard’s expansion slots. Whether the adapter is built into the motherboard or it’s a separate card, you need to check on the drivers that will be used with the adapter because the peripheral devices and the adapter should use the same driver standards.

SCSI drives are more expensive than the IDE drives, but the benefit of using a SCSI drive is its connection. If you need a multitude of drives to create a RAID system, then SCSI is a great solution. If you simply want speed, then you may want to purchase a 7200-RPM DMA/66 drive. It would be a cheap alternative, and the end result would be very similar to using a SCSI drive.

Your selection of a CPU and a hard drive will drastically affect the rest of your PC parts. Once you’ve decided exactly how much power and speed you need in order to get your job done, however, you can make some pretty good choices. In part 3 of this series, I’ll discuss the last two aspects of the computer that you need to consider: the video card and memory.

Paul Suiter received his first taste of the deadline rush as a photographer for the Montgomery Advertiser, where he earned four photography awards. After receiving degrees in economics and business management from Auburn University, Paul entered the college book business. After managing two bookstores for three years, Paul became a business analyst for EDS. Four years later, Paul continues with EDS, taking its equipment apart, while working with G3 switches and advanced imaging programs. But he’s finally getting back to one of his favorite pastimes—writing. (Of course, he also enjoys spending time with his wife and son.)

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