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ECC memory usually involves a higher price when compared to non-ECC memory, due to additional hardware required for producing ECC memory modules, and due to lower production volumes of ECC memory and associated system hardware. Motherboards, chipsets and processors that support ECC may also be more expensive.
Two types of DIMMs: a 168-pin SDRAM module (top) and a 184-pin DDR SDRAM module (bottom). The SDRAM module has two notches (rectangular cuts or incisions) on the bottom edge, while the DDR1 SDRAM module has one. Also, each module has eight RAM chips, but the lower one has an unoccupied space for the ninth chip; this space is occupied in ECC DIMMs.
Two types of DIMMs (dual in-line memory modules): a 168-pin SDRAM module (top) and a 184-pin DDR SDRAM module (bottom). Memory modules of SK Hynix. In computing, a memory module or RAM stick is a printed circuit board on which memory integrated circuits are mounted.
For example, 64 would indicate a 64-bit data width, as is found on non-ECC DIMMs common in SDR and DDR1–4 families of RAM. A memory of width of 72 would indicate an ECC module, with 8 extra bits in the data width for the error-correcting code syndrome. (The ECC syndrome allows single-bit errors to be corrected).
Modern DIMMs can for example feature one rank (single rank), two ranks (dual rank), four ranks (quad rank), or eight ranks (octal rank). [ citation needed ] There is only a little difference between a dual rank UDIMM and two single-rank UDIMMs in the same memory channel, other than that the DRAMs reside on different PCBs .
In other words, LR-DIMMs buffer both control and data lines while keeping the parallel nature of all signals. As a result, LR-DIMMs provide large overall maximum memory capacities, while avoiding the performance and power consumption problems of FB-DIMMs, induced by the required conversion between serial and parallel signal forms. [7] [9
Earlier DIMM generations featured only a single channel and one CA (Command/Address) bus controlling the whole memory module with its 64 (for non-ECC) or 72 (for ECC) data lines. Both subchannels on a DDR5 DIMM each have their own CA bus, controlling 32 bits for non-ECC memory and either 36 or 40 data lines for ECC memory, resulting in a total ...
DDR4 memory is supplied in 288-pin dual in-line memory modules (DIMMs), similar in size to 240-pin DDR3 DIMMs. DDR4 RAM modules feature pins that are spaced more closely at 0.85 mm compared to the 1.0 mm spacing in DDR3, allowing for a higher pin density within the same standard DIMM length of 133.35 mm (5¼ inches).