What are 240pin DDR Dimms?
DDR2 memory modules are currently offered in three frequency ranges, 400MHz, 533MHz and 667Mhz. 240-pin DIMMs are used to provide DDR2 SDRAM memory for desktop computers. Each 240-pin DIMM provides a 64-bit data path (72-bit for ECC or registered modules), so they are installed singly in 64-bit systems. 240-pin DIMMs are available in DDR2 PC2-4200 (DDR2-533) SDRAM or DDR2 PC2-3200 (DDR2-400) SDRAM. To use DDR2 memory, your system motherboard must have 240-pin DIMM slots and a DDR2-enabled chipset.