# DDR2 SDRAM

> second generation of double-data-rate synchronous dynamic random-access memory

**Wikidata**: [Q847146](https://www.wikidata.org/wiki/Q847146)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/DDR2_SDRAM)  
**Source**: https://4ort.xyz/entity/ddr2-sdram

## Summary
DDR2 SDRAM is the second generation of double-data-rate synchronous dynamic random-access memory, a family of computer memory technologies. As a technical standard developed by JEDEC, it succeeded the original DDR SDRAM and offered improvements in performance. It functions as a form of volatile computer data storage.

## Key Facts
- **Classification**: A subclass of synchronous dynamic random-access memory (SDRAM).
- **Generation**: The second generation in the DDR SDRAM family, following DDR SDRAM and preceding DDR3 SDRAM.
- **Standardization**: The technical standard is maintained by the JEDEC standards body.
- **Operating Voltage**: Operates at a standard voltage of 1.8 volts.
- **Aliases**: Commonly known by other names, including PC2, PC2-3200, PC2-4200, PC2-5300, PC2-6400, PC2-7200, PC2-8000, and PC2-8500.
- **Form Factor**: A smaller form factor, DDR2 SO-DIMM, exists for use in devices like laptops.
- **Distinction**: DDR2 SDRAM is a different technology from GDDR2, which is a type of memory used specifically for graphics cards.
- **Bus Frequency**: Operates with a bus frequency of 412.5 MHz.

## FAQs
### Q: What is the difference between DDR and DDR2 SDRAM?
A: DDR2 SDRAM is the direct successor to DDR SDRAM. As the second-generation technology, it introduced technical advancements over the first generation, including a lower operating voltage of 1.8V.

### Q: What voltage does DDR2 RAM use?
A: DDR2 SDRAM modules operate at a standard voltage of 1.8 volts.

### Q: Is DDR2 the same as GDDR2?
A: No, they are different technologies. DDR2 SDRAM is a type of system memory for general computer use, while GDDR2 is a specialized type of memory designed for use on graphics cards.

## Why It Matters
DDR2 SDRAM represents a significant step in the evolution of computer memory. As the JEDEC-standardized successor to DDR SDRAM, it provided the computer industry with a new baseline for performance, enabling faster and more efficient processing for a generation of personal computers. Its introduction of a lower operating voltage (1.8V) compared to its predecessor also contributed to reduced power consumption and heat generation, which are critical factors in system design.

The widespread adoption of DDR2 was a key enabler for more demanding software and operating systems during its era. By defining a clear, interoperable standard, JEDEC ensured that manufacturers could develop compatible motherboards, chipsets, and memory modules, fostering a competitive market and driving down costs for consumers. DDR2's place in the lineage between DDR and DDR3 highlights the iterative, standards-driven progress that defines the development of essential computer components.

## Notable For
- **Generational Successor**: It is officially the second generation in the DDR SDRAM lineage, directly following DDR SDRAM and preceding DDR3 SDRAM.
- **Lower Voltage Standard**: DDR2 standardized an operating voltage of 1.8V, a reduction from its predecessor, which helped lower power consumption.
- **Standardization by JEDEC**: Its specifications were formally defined by the JEDEC standards body, ensuring compatibility and reliability across components from different manufacturers.
- **Distinct from Graphics Memory**: DDR2 is a separate and distinct technology from GDDR2, a memory type developed specifically for the high-throughput demands of graphics cards.

## Body
### ### Classification and Lineage
DDR2 SDRAM is a subclass of the broader **synchronous dynamic random-access memory (SDRAM)** family of technologies. It is a form of **random-access memory (RAM)**, which is used for computer data storage.

As the second-generation standard, its lineage is as follows:
- **Preceded by**: DDR SDRAM
- **Succeeded by**: DDR3 SDRAM

### ### Technical Specifications
- **Voltage**: 1.8 V
- **Frequency**:
    - Memory Cell: 206 MHz
    - Bus: 412.5 MHz
- **Data Transfer Speed**: 52.8 gigabits per second

### ### Naming and Standards
The DDR2 SDRAM standard is maintained by **JEDEC**. The technology is known by several aliases which typically correspond to specific speed ratings:
- PC2
- PC2-3200
- PC2-4200
- PC2-5300
- PC2-6000
- PC2-6400
- PC2-7200
- PC2-8000
- PC2-8500

### ### Form Factors and Related Technologies
- **DDR2 SO-DIMM**: A smaller form factor of DDR2 memory designed for laptops and other small-form-factor systems.
- **GDDR SDRAM**: DDR2 is distinct from GDDR SDRAM types (like GDDR2), which are specifically designed for use on graphics cards. However, some graphics cards, such as the Radeon HD 5450 and Radeon HD 5550, utilized DDR2 memory.

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