Memory - Ddr SdRAM

Ddr SdRAM types

The memory SDRAM standard or Synchronous Dynamic Random Access Memory standard is designed to operate at higher speeds by simultaneously keeping two sets of memory addresses open to allow for alternate data transfer on each set of addresses. The pipelining capability of SDRAM allows for the identification of the exact clock cycle that the requested data will be available, ensuring that the CPU doesn't have to wait between memory accesses.

Synchronous DRAM or SDR SDRAM is essentially having the synchronous interface, which means that the internal clock, bus clock and I/O are all the same. If you have PC133 SDRAM, the internal clock, bus clock, and I/O are all 133 MHz rated. The single data rate implies that the SDRAM can only perform a single read/write command in a clock cycle.

Double data rate (DDR) SDRAM is the second generation, and it offers greater bandwidth compared to the previous generation. That means that the memory module improves performance by doubling the transfer rate without necessarily increasing the frequency of the clock.

The DDR memory has four different generations:

DDR SDRAM is the first generation of the DDR memory and offers double the transfer rates of SDR SDRAM. DDR has a prefetch buffer of 2 bit. The effective transfer rate of the DDR is anything between 266 and 400 MT/s. It explains why you have the options of DDR266 and DDR400.

DDR2 SDRAM (Double Data Rate 2 SDRAM) is the second generation of the DDR which has the improved bus signal functionality to operate the external data bus at double the speed of DDR SDRAM. DDR2 has prefetch buffer of 4 bit but the clock speed at 133 to 299 MHz is similar to that of DDR. However, the transfer rate of DDR2 is anything between 533 and 800 MT/s and improved I/O bus signal. At ALLHDD you can find bulk packs with storage capacity of 8GB and 16GB for a great price.

DDR3 SDRAM is the third generation and has a transfer rate of 800 to 1600 MT/s with a prefetch buffer of 8 bit. DDR3 memory helps reduce power consumption by 40% at 1.5V compared to DDR2 at 1.8 V. The power consumption of a DDR is a high 2.5V. The automatic self-refresh (ASR) and self-refresh temperature (SRT) functionalities allow the memory chip to control the refresh rate as per the temperature variation.

DDR4 SDRAM (Double Data Rate Fourth SDRAM) is the fourth generation of DDR with a higher transfer rate and lower operating voltage at 1.2 V. DDR4 will achieve transfer rates of 2133 to 3200 MT/s. The outstanding feature of DDR4 is the four new bank groups technology that allows single-handed operation at each group. The DDR memory chip will process 4 data within a single clock cycle offering greater efficiency compared to DDR3. Other functions on DDR4 memory are CA parity, cyclic redundancy check (CRC), and data bus inversion (DBI) that improve signal integrity and stability of data transmission and access. We have different DDR4 memory chips for increased performance and more effective memory.
HP A9846A 16GB Memory PC2-4200
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A9846A HP 16GB 8X2GB DDR2 SDRAM Registered ECC PC2-4200 533Mhz Memory Kit. New Bulk Pack.

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HP AB322A 16GB Memory PC-2100
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AB322A HP 16GB 4x4GB 266MHz DDR 266 PC-2100 ECC DDR SDRAM Memory Module. New Bulk Pack.

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HP A6970A 8GB Memory DDR HDRAM
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A6970A HP 8GB PC2100 DDR-266MHz ECC Registered CL2.5 184-Pin DIMM Memory for Integrity RX4640 Server. New Bulk Pack.

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Hynix HMT41GA7AFR8A-PB 8GB Memory SDRAM
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HMT41GA7AFR8A-PB Hynix 8GB 1X8GB PC3-12800 2RX8 DDR3-1600MHZ SDRAM ECC Unbuffered 204-Pin Sodimm Memory Module. New Bulk Pack.

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