DDR2 and DDR3 and different versions of DDR (Double Data Rate version). The major question here is, what is DDR? It is a type of RAM (Random Access Memory). In computer systems, RAM is a temporary memory storage device and it needs RAM for the execution of every small command or process. For instance, if a computer system wants to run a process, it will first look up the RAM for its required data. If it is unable to find the RAM, or the data in RAM, it will then move towards the secondary storage device, i.e. hard disk drive to complete the processing. This fetching of data from hard drive is really time consuming and cannot be ignored in modern computer systems as sluggish computers is not an option in this era.
Comparison Chart of DDR2 and DDR3
| Â | DDR2 RAM | DDR3 RAM |
|---|---|---|
| Clock | The clock frequency of DDR2 is in the range 400 MHz – 800 MHz | The clock frequency of DDR3 is in the range 800 MHz – 1600 MHz |
| Rate of data transfer | The data transfer rate is in the range 400 Mbps – 800 Mbps | The rate of data transfer is in the range 800 Mbps – 1600 Mbps |
| Working/supply voltage | The supply voltage of DDR2 is 1.8V | The supply voltage of DDR3 is 1.5V |
| Abbreviation | Double Data Rate version 2 | Double Data Rate version 3 |
| Market value | Market value of DDR2 is cheaper | It is quite expensive compared with DDR2 |
| Performance | It is better in performance. | Compared to DDR2 it is average in performance, DDR2 is better |
| Power consumption | DDR2 consumes very large amount of power | Power consumption is lesser compared to DDR2 |
| Speed | Speed is slower | Speed is faster |
| Memory reset option | No memory reset option is available. | Memory reset button is available in DDR3 |
The sluggish computer (slow in speed) can be improved by the addition of a new RAM in their processing cycle. After a brief introduction of RAM lets’ now move towards the basics of DDRs. A DDR is one of many types of RAM. DDR RAM is its common name however; it is also known as DDR2SDRAM (Double Data Rata Synchronous Dynamic Random Access Memory 2) and DDR3SDRRAM (Double Data Rata Synchronous Dynamic Random Access Memory 3).
The first Double Data Rate RAM was named so because it was able to transfer two data packets per cycle. With each different version, along with many other differences the major difference was the change in the number of data packets per cycle. For instance, the number of data packets per cycle changes from two to four with a single version upgrade i.e. it was two in the first version of DDR and four in DDR2.
In normal SDRAM (previous version of DDR) the data transfer occurs on only the rising edge of the clock cycle, however in the upgraded version (DDR) the data transfer occurs on both rising as well as falling edge of clock cycles. However, with each version upgrade both the clock edges were already in use, but the data transfer packets can be increased by increasing the clock cycle frequency (double in DDR2 and triple in DDR3). As we move from DDR to DDR5, the clock frequency of the RAM increase by 1-fold each version. Also, in order to make a successful upgrade in the versions of RAM we must also upgrade the hardware i.e. motherboard accordingly. And with the upgrade in the DDR version, the efficiency of machine increases and the performance decreases. Lets’ make it a little more precise and move towards the definition of DDR2 and DDR3 specifically.
DDR2 (Double Data Rate version 2)
In the family of DDR SDRAM, the version 2 is the second in the number of generations. As we have discussed previously in DDR2 the clock frequency of RAM data transfer increases to double, supporting 4 data transfers per clock cycle of previous version of DDR. The buffer of the RAM is a 4-bit cache memory, this buffer was used for the prepositioning of the data bit before processing in order to increase the speed and the operating voltage of the DDR2 is 1.8 V which was a little higher than the operating voltage of DDR3. The reduction in the operating/supply voltage was in order to reduce the heat effects in the latest version.
In the previous version of DDR, the operating voltage was higher and the number DIMM (Dual In-line Memory Module) pins was lesser, and with every upgrade of version in the operating voltage decreases and no of pins increases. In DDR3 the number of DIMM pins is 240. One or more RAM chips are used for the composition of these DIMM’s to form a single board and that single board is connected to the motherboard.
The clock frequency of DDR2 is in the range 400MHz to 800 MHz which was double the frequency of DDR1 and half the frequency of DDR3, and the speed of the transfer of data (data transfer rate) of DDR2 is 0.8GT/s. Among all the available capacities of DDR2 the most common capacity is 4GB however, 2GB of DDR2 is also present. The theoretical background of DDR2 is 6.4 GB/s.
DDR3 (Double Data Rate version 3)
This is the third generation (third version) in the DDR family, and the changes in it goes in the same flow as in DDR2. The prefetch buffer in DDR3 is increased as compared to the buffer in DDR2 and DDR1, i.e. it has a 8-bit buffer for the prepositioning of bits in order to increase speed.
The operating frequency of the DDR ranges from 800 MHz to 1600 MHz which was double the frequency of previous version. The data transfer rate of DDR3 is double than that of DDR2 i.e. it is 1.6GT/s and the theoretical background of DDR3 is 12.8 GB/s.
With every version the operating voltage of the DDR decreases to a specific level same is the case in DDR3, the operating voltage reduces to 1.5V. The number of DIMM pins remains the same however we cannot use them in the same way with motherboard as in the case of DDR2, the difference in version results in the pins configuration with the motherboard.
Conclusion
Both DDR2 and DDR3 are double data rates of ram just a variation in the version or the release. As every software or hardware devices have different versions and the vendor keep on upgrading it on the demand of the consumer or customer so does happen with DDR. According to the need of the users or customers, the former version of DDR i.e. DDR2 needed an upgradation in it, and the version next to 2 was 3 (as is obvious). However, the above discussion gives a briefer and comprehensive difference between their performance, market value and speed or frequency etc.