Guidelines when upgrading memory in Pentium II/III/IV Celeron and Athlon systems

written by: Ing. Hida Hamilton; article published: year 2006, month 07;


In: Categories » Computers and technology » Memory Processor Motherboards and buses » Guidelines when upgrading memory in Pentium II/III/IV Celeron and Athlon systems

These systems are excellent candidates for memory upgrades. Early Pentium II systems often have only 16 MB of RAM. In the price-sensitive consumer Celeron market, many early systems shipped with only 16 MB, and some Celeron systems have been sold with only 8 MB. Expanding memory to 128 MB or more is the most cost-effective upgrade you can make. When upgrading memory in one of these systems, note the following issues:

  • Some early Pentium II and Celeron systems use EDO SIMMs or DIMMs, but most use 3.3 volt 168-pin unbuffered JEDEC SDR-SDRAM DIMMs.

  • Conserve DIMM sockets. A few motherboards have four DIMM sockets, most have three, and some low-end systems have only two. If you have the choice, always install one larger DIMM rather than two smaller ones that total the same amount of memory. Note, however, that older systems may not recognize large-capacity DIMMs or those that use 128-megabit or larger memory chips. In that situation, a BIOS upgrade may help, but the limitation is often hardcoded into the chipset.

  • Most of these systems have nonparity memory installed, but can use either parity or nonparity DIMMs interchangeably. Unless you plan to install 512 MB or more, install nonparity DIMMs. We have been told that when using very large amounts of memory—more than 512 MB—memory errors introduced by cosmic rays make it worthwhile to pay the additional cost for parity/ECC memory and to accept the small performance hit that using ECC produces.

  • Memory must always be added in full banks. These systems use a 64-bit memory bus, and therefore require adding 72-pin SIMMs in pairs. DIMMs may be added individually.

  • Most SIMM-based systems use 60 ns or 50 ns memory. Make sure memory you add is at least as fast as the memory that is already installed. Early DIMM-based systems use FPM or EDO DIMMs, which you should match as closely as possible. Later DIMM-based systems may use JEDEC (PC66) SDRAM. You can install PC66 SDRAM, but it usually makes more sense to buy PC133 SDRAM for these systems because it can be recycled later if you upgrade to a faster system.

legal disclaimer

1) Our website is not responsible for the information contained by this article as well for any and all copyright infringements by authors and writers. E-articles is a free information resource. If you suspect this article for any copyright infringements, please read the Terms of service and contact us to investigate the problem.
2) The E-articles directory team is not responsible for inaccuracies, falsehoods, or any other types of misinformation this tutorial may contain and will not be liable for any loss or damage suffered by a user through the user's reliance on the information gained here. Please read the Terms of service

Useful tools and features

Translate this article to...    Send this article to you or to a friend

Link to this article from your page   
If you like this article (tutorial), please link to it from your web page using the information above. Linking to this page, this is the only way to help us improve our service, the same time providing your visitors with a way to improve their online experience.

related articles

1. EDORAM ~ Extended Data Out RAM
In 1995, a newer type of memory called extended data out (EDO) RAM became available for Pentium systems. EDO, a modified form of FPM memory, is sometimes referred to as Hyper Page mode. EDO was invented and patented by Micron Technology, although Micron licensed production to many other memory manufacturers. EDO memory consists of specially manufactured chips that allow a timing overlap between successive accesses. The name extended data out refers specifically to the fact that unlike FPM, the data output drivers on the chip are not ...

2. Troubleshooting Memory
Memory problems can be difficult to troubleshoot. For one thing, computer memory is still mysterious to people because it is a kind of "virtual" thing that can be hard to grasp. The other difficulty is that memory problems can be intermittent and often look like problems with other areas of the system, even software. This section shows simple troubleshooting steps you can perform if you suspect you are having a memory problem. To troubleshoot memory, you first need some memory-diagnostics testing programs. You already have several, a...

3. How SIMM DIMM and RIMM memory work
Originally, systems had memory installed via individual chips. They are often referred to as dual inline package (DIP) chips because of their designs. The original IBM XT and AT had 36 sockets on the motherboard for these individual chips; then more of them were installed on the memory cards plugged into the bus slots. I remember spending hours populating boards with these chips, which was a tedious job. Besides being a time-consuming and labor-intensive way to deal with memory, DIP chips had one notorious problemthey crept out of th...

4. The evolution of Microprocessors from 1971 to the Present
It is interesting to note that the microprocessor had existed for only 10 years prior to the creation of the PC! Intel invented the microprocessor in 1971; the PC was created by IBM in 1981. Now more than 20 years later, we are still using systems based more or less on the design of that first PC. The processors powering our PCs today are still backward compatible in many ways with the 8088 that IBM selected for the first PC in 1981. November 15, 2001 marked the 30th anniversary of the microprocessor, and in those 30 years processor ...

5. RDRAM
Rambus DRAM (RDRAM) is a fairly radical memory design found in high-end PC systems from late 1999 through 2002. Intel signed a contract with Rambus in 1996 ensuring it would support RDRAM into 2001. After 2001, Intel continued to support RDRAM in existing systems, but new chipsets and motherboards primarily shifted to DDR SDRAM, and all future Intel chipsets and motherboards are being designed for either conventional DDR or the newer DDR2 standard. RDRAM standards had been proposed that will support faster processors through 2006; however, w...

6. Processor Codenames
Intel, AMD, and Cyrix have always used codenames when talking about future processors. The codenames usually are not supposed to become public, but they typically do. They can often be found in online and print news and magazine articles talking about future-generation processors. Sometimes, they even appear in motherboard manuals because the manuals are written before the processors are officially introduced. Processor Coden...

7. What is UMA ~ Upper Memory Area
The term Upper Memory Area (UMA) describes the reserved 384KB at the top of the first megabyte of system memory on a PC/XT and the first megabyte on an AT-type system. This memory has the addresses from A0000 through FFFFF. The way the 384KB of upper memory is used breaks down as follows: The first 128KB after conventional memory is called video RAM. It is reserved for use by video adapters. When text and graphics are displayed onscreen, the data bits that make up those images reside in this space. Video RAM is allotted t...

8. Memory Basics ~ ROM DRAM SRAM Cache Memory
Memory is the workspace for the computer's processor. It is a temporary storage area where the programs and data being operated on by the processor must reside. Memory storage is considered temporary because the data and programs remain there only as long as the computer has electrical power or is not reset. Before being shut down or reset, any data that has been changed should be saved to a more permanent storage device (usually a hard disk) so it can be reloaded into memory in the future. Memory often is called RAM, for random acce...