Tips on How to Choose a Computer Memory Module

• Need memory for a specific laptop, notebook or desktop PC? Try the Kingston Memory Configurator to find specific memory for your configuration.
• 133MHz SDRAM modules, also referred to as "PC133 DIMM," are the latest memory modules available in mass production. They are about the same price as the slower, 100MHz modules, but actually cheaper than 66MHz SDRAM modules. The 133MHz memory modules are back compatible and will work in most 100MHz and 66MHz systems, but the 66MHz won't work in any 100MHz system. The difference between 100MHz and 133MHz is not as great as that between 100MHz and 66MHz. Some 100MHz memory modules are reported working on a 133MHz bus. We suggested purchasing 133MHz memory module whenever possible, even for 66MHz bus-rate systems.
  
  
• RAMBUS memory modules (RIMM in short) are still on the horizon. They are available at relatively high prices, and aren't supported by many motherboards. This type of memory is most commonly used by motherboards supporting the Pentium IV.
  
  
• DDR Memory or Double Data Rate memory, is an evolutionary new memory technology that doubles data throughput to the processor vs conventional Sdram. DDR is viewed as the main competition vs Rambus memory. Because DDR is fairly easy to produce using the same production systems as Sdram it has become quite affordable. It is rapidly gaining popularity.
  
  
• Memory is one thing that we suggest customers not to buy just based on prices alone. The quality of memory modules is extremely critical to computers. This is especially true in a high-speed, 133MHz and 100MHz system. You or your customers will not like seeing "that blue screen" with a "fatal error message" (often a sign of memory problems). Trust me!
  
  
• Buy modules only with the name-brand chipsets that carry the names of the original chip manufacturer! And with LIFE-TIME warranty! Name-brand chipsets include Micron Technology (MT), Texas Instruments (TI), Toshiba, Hyundai (HY), Goldstar (LGS), Samsung (SEC), Siemens, NEC, Panasonic, and Fujitsu.
  
  
• Chipsets on memory modules are very important! Watch the brand on the chips carefully. There are only a dozen or so original manufacturers around the world who are capable of designing and producing memory chips on a silicon level. Such a manufacturing process is very capital intensive. However, almost any "mom-and-dad" shop these days can invest in a memory module machine and start producing cheap memory modules. They often use cheap, off-grade memory chipsets with the original manufacturer names sanded off and some odd-sounding names stamped on. With such cheap memory modules often come high return rates.
  
  
• What're buffered and ECC memory modules? They have an extra bit to every transaction for error checking. They are however about 3% slower than unbuffered memory. These are used mainly for mission-critical systems such as servers. They are often more expensive and not required on most desk-top systems. They are "downgrade" compatible, meaning they will work in a regular system if you happen to have them. Check your system manual to see if it requires buffered and/or ECC memory.
  
  
• What's the difference between CAS2 and CAS3 memory? There is a 0.5 nanoseconds or one half of one billionth of a second in latency difference between them. For stand-alone systems no one would notice any difference at all. However, in a network environment where interactions between a workstation and the server take place often, the difference is significantly magnified. As a result, the less than $10 difference in price is worth it.
  
  
• Some memory module companies stamp their memory modules with their brand names and make a name out of them. Examples are Kingston, PNY, and Century. This is like putting brands such as Sunkist on oranges. It is a good marketing tool through the retail channels. However, don't be confused with original chipset manufacturers. A name-brand module may or may not have the name-brand chipset on it.
  
  
• The effective speed of a computer system is a function of microprocessor speed, size of cache memory, size of RAM memory, hard drive speed, and video card speed. Buy the largest size of memory modules your budget allows. You will not regret it.
  
  
• The computer components industry is notorious in poor labeling. One example is memory modules. The 66MHz, 100MHz, and 133MHz SDRAM modules physically look the same. What's worse, 128MB modules may look exactly the same as 32MB! Yet, they are often not labelled. You can tell the difference between 66MHz and 100MHz by reading the stamping codes on the chipset. (You may have to use a magnifying glass to read them.) "-10" means 10ns and 66MHz. "-8" means 8ns and 100MHz. How to recognize the size of the memory? Only a memory tester or a system testing can tell if it is not labeled clearly. Update: The labeling on memory is getting better. Now 95% of the memory is labeled for frequency and size.
  
  
• There is an industry standard on the design of memory modules, but not all PC manufacturers are following it, especially those "big players." They like to design their own shapes of memory modules for their systems so that the standard memory modules you can buy elsewhere and less expensively, will not fit into their systems. Well, the chip and technology are the same! The only difference may be the shape, which is called "proprietary" and often bear an outrageously high price tag for the end-users. You must have guessed it right why the "big players" have been doing this. Let's hope that only your neighbors are falling into this kind of schemes.
  
  
• Adding more memory modules is probably the easiest and sometimes most inexpensive way to upgrade an existing system.
  
  
• 30-pin and 72-pin parity, fast-page mode (FPM), and even EDO memory modules are things of the past. If you don't have a 386, 486, or low-Pentium system to consider upgrading instead of throwing away, you really do not need to know what these terms mean.
  
  
• 72-pin EDO memory modules are 16bit technology, but Pentium systems that use EDO memory are 32bit. Therefore, EDO memory must be used in pairs so that two banks of memory are combined to allow 32bit processing. Unless you already have a piece of EDO memory, we suggest you purchase EDO memory in pairs for upgrade purposes. Because they have to work together, we suggest using only identical pairs.