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What's inside your computer

Shopping for a computer requires some homework.

Consumers need to understand the terminology used by sales reps and in ads so they can make an informed decision about whether a particular machine is right for them. Buying a computer is different from most consumer appliances, with a language all its own.

Here's a guide to what's inside a computer, as well as my recommendations of what to look for when you shop:

Central processing unit (CPU): It's the main processing chip and plays a large part in how fast your computer will run. The speed is measured in megahertz (MHz), which stands for thousands of cycles per second, and gigahertz (GHz), which stands for millions of cycles per second. Now, more than ever, the types of CPU chips and speed options are numerous and potentially confusing. However, you don't need to understand terms such as Hyper Pipelined technology, Net Burst or branch prediction. You just want to know how fast it is and, more important, whether it will be sufficient for your computing needs. Intel (Celeron, Pentium III and Pentium 4) and AMD, or Advanced Micro Devices, (Duron and Athlon) are the two main companies that produce CPU chips for most IBM-compatible computers.

L2 level cache: Cache memory is high-speed memory built into the CPU chip, designed to accelerate processing of data and instructions by the chip. (L2 is the second level of cache available on a chip. All of today's chips come with the first level, called L1.) Without sufficient L2 cache, the full speed of the CPU chip isn't utilized. It also is one of the most expensive areas of chip production, which is why less L2 cache equals lower prices.

Intel's CPU chips: Intel's entry-level CPU chip is the Celeron. It likely will be part of any Intel-powered sub-$1,000 PC available. It comes in speeds ranging from 766MHz to to 1GHz.

Don't let the fact that the Celeron doesn't carry Intel's better-known Pentium name fool you. Architecturally, the Celeron is very similar to the Pentium III with a smaller L2 cache and a 66MHz FSB (Front size bus or system bus. Think of the system bus as a vehicle used to transfer data between the CPU and main memory and other components).

The Pentium III comes in speeds from 800MHz to 1.1GHz. Although the Pentium III has a bigger L2 cache than the Celeron and a faster FSB at 133MHz, there is overlap between the high-end Celerons and the low-end Pentium IIIs. In this case, let some of the other peripheral equipment that's included help you make the decision.

Intel's fastest chip, the Pentium 4, comes in speeds from 1.3GHz to the recently released 2GHz. It is geared to improved performance for the Internet, imaging, streaming video, speech, 3-D and multimedia with the inclusion of what is referred to as SSE2 (Streaming SIMD extension 2) instructions. These are new instructions built into the chip that help make quick work out of all types of multimedia processing. Along with these architectural improvements is the increased system bus speed of 400MHz, almost three times the current speed of the Pentium III systems.

All of these architectural changes sound very impressive, but most of the Pentium 4 benchmarks have been underwhelming, barely outrunning the Pentium III and running neck-and-neck with the higher-end AMD Athlon chips. Without a doubt, the Pentium 4 is an improvement over its predecessor, the Pentium III, but you may need to justify costs in some cases, especially when considering systems built with high-end Athlons.

AMD chips: AMD is the other major manufacturer of CPU chips. Its main offerings are the Athlon and Duron. They are roughly equivalent to Intel's Pentium III and 4 and Celeron respectively. Not long ago AMD was considered the underdog, far behind Intel in both technology and market share. But things have been changing. With their larger L1 and L2 cache, the Athlon and Duron chips are considered by many to be technologically superior to their Pentium III and Celeron counterparts. High-end Athlons in speeds of up to 1.7GHz compete very well with the Pentium 4. This is very good for the PC-using public, as competition has helped keep prices down.

At the same time, these increased choices have to be confusing for a public not expertly versed in microchip technologies. So what order then can we put these varying chips in?

Let's start at the top: The 2GHz Pentium 4 is king of the hill. Next would be the 1.7GHz Athlon, followed closely by the Pentium 4 in speeds from 1.4- to 1.7GHz. Next would be Athlon in speeds from 1- to 1.3GHz, then the Pentium III from 800MHz to 1.1GHz. Let's consider the entry-level Celeron and Duron to be equivalent, megahertz for megahertz, with maybe a slight edge to the Duron for having the newer technology.

Keep in mind this rating is subjective, and any rating can be skewed depending upon which benchmark reports you read. Use it as a general guide and, as long as the systems you're comparing are in the same ballpark on speed, use other factors such as price, features and equipment to help you make your choice.

Random access memory (RAM): As your computer runs programs and works with data, it uses RAM to hold this information. Measured in megabytes (MB), RAM is often the most important factor of overall system speed. When Windows runs out of physical RAM, it starts using space on the hard drive to create what is referred to as virtual memory. When this happens, even the fastest CPU will slow to a crawl. Some systems come with only 64MB of RAM. Be clear about this: That's not enough. The Windows Me operating system along with the Internet Explorer Web browser will consume more than half this amount, and the computer will immediately start slowing as Windows uses your hard drive as virtual memory. With just basic services loaded, the business-oriented Windows 2000 Professional can consume 100MB of RAM by the time it boots and is ready for use. Don't even think about running with less than 128MB.

The bare minimum for RAM these days is 128MB, with 256MB or more highly recommended, particularly for the new Windows XP. If you work with large digital graphic or video files, having more than 256MB of RAM is not excessive. Without a doubt, RAM is the area where you'll get the most performance bang for the buck. RAM prices have dropped dramatically from last year and have never been cheaper. A 256MB SIMM (single inline memory module) can be bought for less than $50, even less with rebates. RDRAM (Pentium 4) and DDR SDRAM (266 FSB Athlon) are a little more expensive. It will be money well spent. Don't skimp.

Hard disk: Here is where you store your programs and data. It's measured in gigabytes (GB), each equal to 1,024 megabytes, and bigger is better. Sizes as large as 80GB are becoming common in newer systems, and 20GB should be the absolute minimum. If you work with graphics, digital photos or music, you'll want the larger sizes. UltraATA/100 drives are the high-speed standard. As the name implies, the transfer rate of an ATA/100 disk drive is 100MB per second. The faster a disk spins, the faster the data is passed over the read-heads and returned to the system, so drives with spin rates of 7200 RPM (revolutions per minute) are faster (and more expensive) than drives with 5400 RPM spin rates. Again, if you do a lot of graphics and photo-editing work, the UltraATA/100 7200 RPM drives will provide much better performance.

Monitor: The window into your computing world, I consider this one of the most important parts of your computer purchase. However, sometimes it's better to consider it separately from your main computer purchase. Good monitors can last through a couple of computer lifetimes, so you don't necessarily have to buy a new one when you upgrade. You can look at it as an investment beyond just your first (or next) computer purchase.

I recommend buying the best quality you can afford. A general rule is the flatter the screen, the better the quality. Flat screens of all sorts, not just the very expensive liquid crystal diode (LCD) models, cost more to produce and offer much less distortion and bend in the corners. If those problems show up, it usually is a sign of an inferior monitor. Some other things to look for:

_ Size: A 17- to 19-inch screen (measured diagonally, subtract about an inch to get actual viewing area) is probably the most popular size and works well for most types of applications. Serious graphic designers and game players will want at least 19 inches.

_ Resolution: Most computers use a screen resolution of either 800 by 600 pixels on smaller monitors and 1024 by 768 on larger one (17 inches or above). The resolution is the number of pixels in the horizontal and vertical directions. The higher the resolution, the more information you can see on the screen at once, and in more detail.

_ Refresh rate: This refers to the number of times a monitor redraws the screen each second. Higher refresh rates mean less flicker on the screen and less strain on the eye. Refresh rate is irrelevant on LCDs, which are usually optimized for a fixed resolution. Regardless of which size you choose, make sure your monitor is capable of at least 1024 by 768 resolution and a 75MHz refresh rate.

_ Dot pitch: The distance between the phosphors that make up a pixel, measured as a fraction of a millimeter. Again, this does not apply to LCD displays. In general, the smaller the pitch, the sharper the image. Look for a horizontal dot pitch of 0.25mm or less.

_ Flat-panel LCD displays: You pay at least $300 to $600 over what you would pay for a conventional CRT monitor of the same size. If the extra money is not a factor, this is definitely the recommended path. The clarity and brightness far surpass even the best conventional monitor, not to mention the extra room you pick up because it takes so little space on a desk compared with the giant CRTs. Keep in mind that a 15-inch LCD is nearly equivalent to a 17-inch CRT screen in viewable area.

Video card: All new computer systems come with an Accelerated Graphic Port (AGP). AGP was introduced a few years ago and is now the standard interface for the home computer platform. It dramatically improves the processing of 3-D graphics and full-motion video. AGP 4X delivers twice the bandwidth of AGP 2X.

Video cards have their own RAM (measured in megabytes). The more RAM a card has, the faster it can process and display information, as well as produce higher resolutions. Here, 4MB is the minimum. If you don't do much with graphics or games, it will be sufficient. Otherwise, look for one with at least 16- to 32MB. If you do a lot of photo editing, play 3-D games or plan on adding a TV-tuner card (which lets you watch TV on your monitor), look for one with 32 to 64MB of RAM and 3-D acceleration capabilities. Note whether the video RAM is shared, which means it borrows from the system RAM for the rest of your PC's operations, reducing what's available. This is common on systems that have what is referred to as integrated video. This means the video controller is built into the motherboard. If you're a serious gamer or do intensive graphic or video work, integrated video is not for you.

Sound card: If you're not into playing games or music CDs, almost any sound card will do. Otherwise, make sure your sound card uses Wavetable technology rather than FM Synthesis. Wavetable technology produces a clearer, more lifelike sound. The better cards also should support DirectSound3D. No matter how good your sound card is, the quality of the sound will be determined in large part by the quality of the speakers. Speakers that include a subwoofer will be able to greatly enhance the deep bass sounds. A little extra money usually goes a long way in getting better quality sound from computer speakers.

CD-ROM: The speed of a CD-ROM (compact disc, read-only memory) is measured in spin rates, with higher numbers being faster. They change almost daily, and most are in the 17X to 56X or higher range.

DVD-ROM: It can hold much more information than a normal compact disc (up to 6 gigabytes versus 700 megabytes). This will allow software titles that previously used multiple CDs to be contained on one disk. Movies also are available in DVD, but unless you want to watch a feature-length movie sitting around your PC, get one with jacks that will connect to your TV. DVD is backward compatible with CD-ROM and audio CDs, so your existing CDs will be recognized by your DVD-ROM. Therefore, there is no reason to buy a system with a standard CD-ROM. Spend a little extra and upgrade to a DVD-ROM, even if you currently don't have any DVDs. DVD-ROM speed is measured in spin rates, one for reading DVDs and another for regular CDs. DVD-R/RAM devices for recording DVDs also are available, but are still very expensive. The QPS USB 2.0 DVD recorder sells for nearly $700.

CD-RW: With a CD-RW (compact disc, rewriteable) device, you can record data on a CD, erase it and then re-record it up to 1,000 times. CD-RW can use two different types of compact discs (also called media). CD-R, or write-once, media can

sell for 33 cents or less each, while CR-RW, or reusable, media sell for $1 or less each. Both will work in a CD-RW drive. Recordable CD devices are good for making music CDs or saving photos or other data that won't fit on a regular floppy disk. It's also a good alternative for backing up what's on your computer's hard drive.

Backup: I personally don't know any home PC users that dutifully back up their data (but I'm sure they're out there). That's probably due to the fact that today's hard drives are so dependable. But there are risks besides mechanical hard drive failures, such as destructive viruses and accidental erasure. You need to provide for some kind of backup media. A CD-RW drive or Iomega's 2GB Jaz drive are great alternatives for large amounts of data, and 250MB Zip drives could be sufficient for smaller systems. Remember, you don't need to back up your whole system, just whatever can't be reproduced from original media. If you get in the habit of keeping all the documents and media you create in My Documents folders, it will make backup much simpler and more straightforward.

Modem: To hook up your computer to the Internet, most new systems include a modem that claims speeds up to 56 kilobits per second (what's known as a 56K V.90 modem). Actual transmission speeds don't reach that level, though, due to phone line limits. Some modems also can send and receive faxes at 14.4Kbps. But these traditional modems soon will be considered about as useful as old 5.25-inch floppy disk drives. High-speed Internet access is becoming more popular and more widely available for home use, either through your cable TV or through your phone lines as a digital subscriber line (DSL). The specialized modems for such connections are provided by the cable or phone companies offering the service, although you also can purchase them yourselves and maybe save some rental fee.

Universal Serial Bus (USB) ports: These are standard on all new PCs. The list of equipment that uses the USB connections has grown to include almost any peripheral you'd care to hook up to your computer, such as a mouse, printer, scanner, cameras, CD-RW and even an extra hard drive. Low-price USB hubs allow you to string together a number of devices once you use up the two connections that come with most computers. Just starting to become available is USB version 2.0. This next generation of USB extends the speed of the peripheral-to-computer connection from the current 12 megabits per second to 480Mbps, or 40 times faster. USB 2.0 is backward compatible (your older USB devices still will work). However, only devices made specifically for USB 2.0 will be able to take advantage of the increased throughput.

When evaluating smaller PCs that have fewer expansion slots, keep in mind that many of the peripherals you would normally use expansion slots for, such as network cards, modems and TV-tuner cards, are available in USB format.

FireWire: It's also known as IEEE 1394 (IEEE stands for the Institute of Electrical and Electronics Engineers) and is a serial interface similar to Universal Serial Bus. Both offer hot plug capability, eliminating the need to restart the computer when a new peripheral is attached. The current FireWire standard transfers at rates up to 400 megabits per second, much faster than USB 1.0, which tops out at 12Mbps. However the new USB 2.0, with its increased speed, may make the future of FireWire uncertain. As with USB, FireWire devices provide their own bus power, which means that no power plugs are usually needed. FireWire devices include disk drives, CD-RW and DVD-RAM drives, printers, scanners and digital editing equipment. FireWire is the preferred interface for serious digital video editing users.

Mouse: I'm hooked on the optical mouse, which was introduced last year. I'll never buy another mouse pad again. The new optical mouse uses a tiny digital camera to take 6,000 frames per second of the surface beneath the mouse. A digital signal processor analyzes these pictures and translates movement of the mouse into crisp movement of the cursor on your computer screen. What this means is no more mouse pads or moving parts on the mouse that need to be cleaned. Its movements also are much more precise.