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Double Data Rate 2 Synchronous Dynamic Random-Access Memory (DDR2 SDRAM) is a double data rate (DDR) synchronous dynamic random-access memory (SDRAM) interface. It is a JEDEC standard (JESD79-2); first published in September 2003. [2] DDR2 succeeded the original DDR SDRAM specification, and was itself succeeded by DDR3 SDRAM in 2007.
DDR2 started to be effective by the end of 2004, as modules with lower latencies became available. [ 19 ] Memory manufacturers stated that it was impractical to mass produce DDR1 memory with effective transfer rates in excess of 400 MHz (i.e. 400 MT/s and 200 MHz external clock) due to internal speed limitations.
DDR and DDR2 memory is usually installed in single- or dual-channel configuration. DDR3 memory is installed in single-, dual-, tri-, and quad-channel configurations. Bit rates of multi-channel configurations are the product of the module bit-rate (given below) and the number of channels.
The naming convention for DDR, DDR2 and DDR3 modules specifies either a maximum speed (e.g., DDR2-800) or a maximum bandwidth (e.g., PC2-6400). The speed rating (800) is not the maximum clock speed, but twice that (because of the doubled data rate). The specified bandwidth (6400) is the maximum megabytes transferred per second using a 64-bit width.
DDR2 DDR3: Callisto 545, 550, 555, 560, 565, 570 2/4 3000–3400 2000 HT 512 6144 DDR2 DDR3: Athlon II: Propus 4 2200–2800 2000 HT 512 DDR2 DDR3: MMX, SSE, SSE2, SSE3, SSE4a, Enhanced 3DNow! Cool'n'Quiet: AMD64, NX bit, AMD-V: Rana 3 2200–3100 2000 HT 512 DDR2 DDR3: Regor 2 1600–3600 2000 HT 512, 1024 DDR2 DDR3: Sempron: Sargas 130 1 2600 ...
Corresponding 240-pin DIMMs are known as PC2-3200 through PC2-6400. DDR2 SDRAM is now available at a clock rate of 533 MHz generally described as DDR2-1066 and the corresponding DIMMs are known as PC2-8500 (also named PC2-8600 depending on the manufacturer). Performance up to DDR2-1250 (PC2-10000) is available.
Memory clock then determines the final operating frequency or effective clock speed of memory system depending upon DRAM types (DDR, DDR2 and DDR3 SDRAM). By default, FSB speed and memory are usually set to a 1:1 ratio, meaning that increasing FSB speed (by overclocking) increases memory speed by the same amount. Normally system memory is not ...
1GB 2Rx4 PC2-3200P-333-11-D2 is a 1 GB DDR2 Registered DIMM, with address/command parity function, using 2 ranks of x4 SDRAMs operational to PC2-3200 performance with CAS Latency = 3, tRCD = 3, tRP = 3, using JEDEC SPD revision 1.1, raw card reference design file D revision 2 used for the assembly.