A Primer on PC Memory

If the above paragraph is gobbledegook to you, here's help (and a glossary, if any of the terms below don't make sense either.) Or, if you prefer, jump directly to our recommendations.

The Basics

PC memory can significantly improve your system's performance.

• Window 95 or 98 require a minimum of 64 MB to really run properly
• Windows NT needs twice as much - 128MB should do the trick
• Going from 32MB to 96MB increases performance up to 42%
• Adding 32 MB of RAM can save up to $541 over a processor upgrade, with faster results!

Upgrading to just 64 MB of RAM doubled - and in some cases tripled - performance in tests using Adobe Photoshop. Additional upgrades yielded even greater increases.

Computers R Us has put together a beginner-friendly primer that's a good place to start researching to topic of memory upgrades. And then, when you're ready....

Beyond the Basics

Today's motherboards that run at a bus speed of 100 MHz are designed for a special type of synchronous dynamic random access (SDRAM) memory commonly called PC100. These PC100 modules are usually in a form called a DIMM - a dual inline memory module. DIMMs differ from SIMMs (single inline memory modules) in that you can insert a single DIMM to upgrade your computer's memory; SIMMs must be inserted in matching pairs. You can use PC100 on a motherboard designed for 66 MHz bus operation, but there isn't much point. It doesn't improve performance and PC100 memory typically costs more than 66 MHz memory.

It is also a fact that, in most cases, you can successfully use memory rated at 66 MHz on a machine with a 100 MHz bus. However, you may encounter reduced reliability including crashes and/or other problems.

In some cases, however, a motherboard running at 100 MHz will display an error message that warns that there is a problem with the "SPD value" of your systems' memory. This so-called "serial presence detect" warning message is a special feature of some motherboards such as the Abit BH6 motherboards. This message disappears when SPD enabled PC100 memory is used and, as stated above, the SPD firmware on the module informs the motherboard of the module's capabilities. Overclockers running at 75 or 83 MHz won't see this message and shouldn't encounter any problems.

Another issue is, as our opening paragraph states, the "CAS" value of the memory. CAS, which stands for column address select -- or column address strobe -- is an issue which primarily concerns those who want the fastest possible performance. Simply put, the best DIMMs are said to be "CAS2." These modules have a sticker, as shown here, that identifies them as PC100-222-xxx.

Shikatronics is a Quebec-based manufacturer of CAS2 memory. One of its memory chips and the sticker on it is shown here. Details at www.shikatronics.com.

Our motherboard specs section lists several recommended manufacturers. For best results, use a recommended configuration of high-quality memory in your computer. Don't skimp when your entire system's reliability is at stake.

How Much RAM?

At the time of its release, Microsoft touted 32 MB as the optimal amount for Windows 95. With the new features of Windows 98 and its increasingly memory hungry web browsers, Office suites, games and other applications, we think 64 MB is the optimum amount for average users. Hard disk "thrashing" is greatly reduced from 32MB configurations. However, a growing number of applications are able to take good advantage of more memory, despite a Windows 9x architectural flaw that actually slows down some functions of the operating system if more than 64MB of memory is installed. We'd definitely recommend 128MB or more for users running Windows NT, Windows 2000, Linux or BeOS, and/or using memory hungry apps such as Photoshop or 3D Studio MAX. Whether you're using a PC or a Macintosh, you'll experience better performance from graphics-hungry applications when more memory is available.

Recommendations

Which PC/100 SDRAM should you buy? Experts say memory from Samsung, Micron, Toshiba, American Megatrends, Corsair, NEC, and Texas Instruments (in that order) is the most reliable. 7 or 8ns memory is considered more reliable than 10ns, but of course costs more.  As customers are increasingly better informed and demanding of reliable components, the higher-quality alternative can be a point in a dealer's favor -- and a few extra dollars in the till. A good source of info on how to buy the fastest PC100 RAM is www.pc100.com. To summarize, the author notes that the parts that will operate at cas 2 @ 100 MHz are the fastest parts. Samsung DIMMs that have a PC100-label saying "222-620" are the fastest, he says, and are rated at 125MHz (max), supporting CAS 2 @ 100 MHz. Next best, he says, is GoldStar's SDRAM, also labeled 222-620. This memory is also reliably capable of CAS 2 @ 100 MHz, and is rated for a max. of 100 MHz. Most others aren't.

What's Next

As we note in our report elsewhere on this site on the Intel i820, Intel's next-generation chipset announced in Nov. 1999, there is a new (well, sort of new -- Intel first announced these plans back in Dec. 1996) type of memory known as Direct RAMBUS memory, or RDRAM. With it, motherboards based on the i820 chipset will provide memory speeds of up to 1.6GB/sec, yielding better overall system performance. So say goodbye to your standard RAM, EDO, SIMMs and other current memory types. Although some motherboards based on the i820 were designed to support PC100 DIMM memory modules, Intel in May 2000 pulled these models from the market after finding that data corruption could occur. See our look at the Camino Chipset for additional details.