RAM explained: What about newer types of RAM?
Today's computers have such fast processors that new types of memory are being developed just to keep up with them. RDRAM (or Rambus), a faster memory originally designed for graphics applications, has now found its way into some cutting-edge (1GHz and more) systems.
However, if you go with RDRAM, you won't be able to simply swap out your SDRAM DIMMs and plug Rambus memory in their place. To take advantage of the RDRAM, your computer's motherboard must have a chipset with the proper Rambus circuitry that can support it.
RDRAM is packaged in RIMMs (Rambus in-line memory modules), which are roughly the same size and shape as DIMMs. A number of manufacturers, including Hitachi, IBM, Kingston, Micron, NEC, Samsung, Toshiba, and Viking, are already in the RIMM business. One feature that's particular to RIMMs is a heat sink. Since individual chips are mounted more closely together on RIMMs than on DIMMs or SIMMs, manufacturers had to come up with a way to direct heat away from them. That's where the sink comes in.
Another newcomer to the RAM game is DDR SDRAM (double-data-rate SDRAM). DDR SDRAM is roughly twice as fast as standard SDRAM, and like RDRAM, it is not compatible with older systems. If you want to upgrade your RAM to DDR SDRAM, your PC's motherboard needs to support 184-pin DIMM slots, and your processor must be fast enough to handle the extra bandwidth (1GHz and faster AMD Athlon chips are examples); otherwise, all that speed just goes to waste. PC1600 DDR SDRAM is made for motherboards and processors with a 200MHz (100MHz doubled) bus, and PC2100 DDR SDRAM is designed for motherboards and processors with a 266MHz (133MHz doubled) bus. PC2100 RAM will work on motherboards with a 100MHz bus, but you won't see any dramatic boost in performance.
For a complete listing of motherboards that support DDR SDRAM, see this list from Crucial Technology.
Glossary terms
DDR SDRAM (double-data-rate SDRAM): DDR SDRAM is similar to SDRAM, but it transfers data on the rising and falling edges of the system clock, theoretically doubling the speed of SDRAM. Though DDR SDRAM was originally developed for graphics cards, desktop PC manufacturers are beginning to use it as a faster alternative to SDRAM.
DRDRAM (direct Rambus DRAM; formerly RDRAM): A type of SDRAM developed by Rambus, DRDRAM is used with high-end Intel CPUs. Like DDR SDRAM, it transfers data on the rising and falling edges of the clock cycle. DRDRAM also uses two data channels to improve transfer rates. In a Pentium 4 system, DRDRAM is often called PC800 and is based on doubling the Pentium 4's 400MHz bus. Note: DRDRAM is more expensive than DDR SDRAM. |
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