Computer 512 MB PC333 DDR Memory - This is a breakthrough offer on the new standard in lightning-fast performance---DDR memory! Twice the speed of SDRAM, and now available from the guaranteed lowest prices! And of course, you'll get 100% reliability.DDR (Double Data Rate) Synchronous is the hottest, fastest new memory technology. The secret to DDR memory's high performance is its ability to perform two data operations in one clock cycle---providing twice the throughput of SDRAM. Yes, TWICE the throughput! DDR SDRAM memory technology has evolved from mainstream PC100 and PC133. This new memory technology enables a new generation of higher performance computer systems, including desktops, workstations, servers, and notebooks. It's no wonder that high-speed DDR memory technology is currently widely used in high-performance graphic adapters. DDR DIMMs have the same physical dimensions as SDRAM DIMMs, but have a different footprint that uses 184 pins compared to 168-pin SDRAM DIMMs. Therefore, DDR memory technology is not backward-compatible with SDRAM and requires motherboards and systems especially designed for DDR.