MemoryPig.com

• Two matched single sticks of premium brand-name 512MB PC2700 DDR-333 Non-ECC unbuffered memory.
  
  Maximum Memory for Optiplex GX270: 4GB
  
  Memory Slots: 4 (two banks of two)
  
  Note: Memory for the Optiplex GX270 does not need to be installed in pairs.  All of the memory sticks we sell are low density which means the highest compatibility possible not only with the Optiplex GX270 but other DDR systems.
  

DDR SDRAM (double-data-rate synchronous dynamic random access memory) is a class of memory integrated circuits used in computers. It achieves nearly twice the bandwidth of the preceding "single data rate" SDRAM by double pumping (transferring data on the rising and falling edges of the clock signal) without increasing the clock frequency.

With data being transferred 64 bits at a time, DDR SDRAM gives a transfer rate of (memory bus clock rate) × 2 (for dual rate) × 64 (number of bits transferred) / 8 (number of bits/byte). Thus with a bus frequency of 100 MHz, DDR SDRAM gives a maximum transfer rate of 1600 MB/s.

JEDEC has set standards for data rates of DDR SDRAM, divided into two parts. The first specification is for memory chips, and the second is for memory modules. As DDR SDRAM is superseded by the newer DDR2 SDRAM, the older DDR version is sometimes referred to as DDR1 SDRAM.