If memory serves

Entrepreneur, April, 1997 by Cheryl J. Goldberg

Just a few years ago, the conventional wisdom said that upgrading your existing PC system often made sense. You could easily add a few years of life to your system by upgrading your hard disk, CPU, memory or graphics adaptor. But with today's exceedingly fast-paced changes in computer technology and free-falling prices, that no longer holds true.

"You can get a system for $1,800 this year that cost $4,000 a year ago," says Jim McGregor, senior analyst for In-Stat, a market research and consulting company in Scottsdale, Arizona. "So now I'd say, 'Get as much system as you can, use it as long as you can, and then move on to a new system."

McGregor cites just two exceptions to that rule: adding memory or a faster modem. Modems were spotlighted in last month's "Business Bytes"; this month, we focus on what adding memory, or RAM, can do.

RAM temporarily stores programs, data and processed information in memory cells as it moves to and from the processor, video card and other peripherals. If you don't have enough high-speed RAM, your computer will temporarily store your data or applications in virtual memory - meaning it uses your hard drive. Because hard drives use mechanical (rather than electronic) methods to store and retrieve information, using virtual memory significantly slows down your system. Conversely, adding RAM can vastly improve application speed.

The good news for potential buyers is that memory prices have been plummeting over the past year - you can currently get a RAM upgrade for about $6 or $7 per megabyte.

* WHEN TO UPGRADE

Memory is always on every techie's list of top upgrades. But that doesn't mean you should automatically add memory to a slow machine. "If your system is less than a 486, sell it," advises McGregor. "It's technologically incompatible with Windows 95."

Similarly, if you have a brand-new machine, you probably won't need to upgrade memory, either. Most computer manufacturers have begun loading new machines with 24MB or 32MB RAM, which is more than adequate for most requirements. It's certainly more than today's applications can use, and it will probably take a year or two before typical applications start requiring that much memory. Even then, probably only the traditionally memory-hungry applications such as games, multimedia or videoconferencing will require additional memory.

Where you may start needing more memory is if you habitually use several applications at one time in different windows. For the most part, memory is a good upgrade. If you have an older Pentium model, or if you have a 486 with 4MB to 8MB RAM, you can probably get another year out of it.

* DO IT YOURSELF?

Determining which type of RAM you need, however, isn't easy. With so many types, in many speeds, sizes and capacities, it's easy to buy the wrong kind.

The type of RAM you'll be upgrading is called DRAM (Dynamic RAM). If you own a brand-name PC, upgrades will be relatively straightforward. Call a reputable memory vendor, and tell them your PC's brand and model. The company should be able to find RAM modules that fit your system.

But if you have a no-name clone or want to buy your memory at a computer superstore, you'd better know what you're doing. Here are the factors you need to consider:

* SIMMs and DIMMs: First, you need to know whether your computer uses SIMMs (single in-line memory modules) or DIMMs (dual in-line memory modules). A SIMM or DIMM is a plug-in board with a number of RAM chips that fits into a socket on the motherboard. SIMMs come in 30- or 72-pin varieties, while the newer DIMM design has 168 pins. If you have a 486 PC, you're probably using SIMMs with either 30 or 72 pins. Pentium PCs usually use 72-pin SIMMs or 168-pin DIMMs.

* Pins: These are tiny vertical gold bars at the bottom of the memory module. The easiest way to find out how many you have is to remove the PC's cover and measure the size of the module. A 30-pin SIMM is just over 3 inches long, a 72-pin SIMM measures a bit over 4 inches long, and DIMMs are about 5 inches long.

* Memory speed: Most of today's PCs use either 60- or 70-nanosecond (ns) RAM. To determine which speed your computer uses, consult your PC's manual or technical specifications, or ask your vendor. If your PC requires 70ns RAM, you can use the faster 60ns chips, although you won't get any speed advantage. Don't buy RAM that's slower than required because it won't work in your system.

* Memory banks: When you add RAM modules to your PC, you'll need to fill an entire memory bank. On some PCs, one bank can hold four SIMM slots; on others, two SIMMs or one DIMM fill up a bank. If you can't tell by looking at the motherboard, check its documentation to determine what constitutes one memory bank in your PC. If your memory banks are full, you'll need to replace your existing RAM with higher-capacity SIMMs or DIMMs.

Remember, you can't mix memory of different capacities, such as 1MB and 4MB SIMMs, in the same bank. You can, however, mix them in terms of having, say, one bank full of 1MB SIMMs and another bank full of 4MB SIMMs.