What is the difference between DDR2 and DDR3?

Dec 6, 2018 771Browse 0Like 0Comments

DDR2 and DDR3 are DDR RAM memory versions, among which DDR3 is a more advanced version with higher functions, such as high data transmission speed, low power consumption, memory reset options, more memory, etc. But the main difference is that DDR3 provides data rates twice as fast as DDR2.

As technology advances, faster memory versions, such as DDR (double data rate) memory, have also been developed. The main concept behind DDR memory is to simultaneously access a large number of bits in the chip by applying row addresses to the chip.

There are several technologies that can improve bit transfer speed from pin to chip. In order to effectively utilize clock speed, data is transmitted externally to the rising and falling edges of the clock, which is why these memories are called double data rate memory.

Clock frequency (theoretical)400 - 800 Mhz800 - 1600 Mhz
Transfer data rate400 - 800 Mbps800 - 1600 Mbps
Supply voltage1.8 volts1.5 volts
Prefetch bit width4 bit8 bit
Memory reset optionNo provision of reset optionsProvided
Power consumptionHighLow
SpeedSlower comparativelyFaster
Latency2 - 57 - 11
PerformanceBetter than DDR3Average

Definition of DDR2

DDR2 is the second version of DDR (double data rate) memory. These versions of RAM were developed to achieve high data rates for block transmission. It can transmit data at a clock rate of 400 to 106 Mhz.

DDR version 2 is a follow-up version of DDR, which mainly changes the operating frequency of RAM chips and prefetch buffers, and the number of both parameters has increased. The prefetch buffer is a 4-bit memory cache that resides in the DDR2 RAM chip. Buffers are used in RAM chips to reserve bits in the data bus as quickly as possible.

DDR2 is a 240-pin DIMM (dual in-line memory module) architecture with a working voltage of 1.8 volts. These DIMMs consist of one or more RAM chips connected to a single board on the motherboard. The voltage of DDR2 is reduced from the previous DDR technology to eliminate the thermal effect.

DDR is designed with 144 pin DIMM and its working voltage is 2.4 volts. There is no compatibility between DDR2 and DDR because they use different motherboard slots and DIMM keys.

DDR3 defines

DDR3 as an advanced version of DDR2, which can increase the prefetch buffer to 8 bits and work at a rate of up to 1600 Mhz. However, the power has been reduced to 1.5 volts, which also reduces the high-frequency heating effect. DDR3 pin architecture also has 240 pins, but these pins can not be used for DDR2 motherboard RAM due to different gap keys.

In DDR3, there is a unique option to remove and reset memory through software reset operation. The memory reset option ensures that memory is cleared and emptied after rebooting the system.

Main differences between DDR2 and DDR3

  1. DDR2 memory operates at frequencies ranging from 400 to 800 Mhz, generating data rates up to 800 Mbps. In contrast, DDR3 operates from 800 to 1600 Mhz with a data transmission rate of up to 1600 Mbps.
  2. DDR2 consumes more power because it provides 1.8 volts. On the contrary, for DDR3, the voltage provided is 1.5 volts, less than DDR2, and the heating effect caused by high frequency is also significantly reduced.
  3. The prefetch buffer size in DDR2 is 4 bits, while DDR3 contains 8 bits.
  4. Memory reset options are available in DDR3, but not in DDR2.
  5. DDR3 is faster than DDR2.
  6. Compared with DDR3, DDR2 has lower latency and better performance.
  7. DDR3 is more expensive than DDR2.

Sum up

DDR2 is an early version and an outdated technology. DDR3 is a follow-up product of DDR. DDR3 is improved and provides more functions, such as larger storage space, lower power consumption, faster clock speed and system flexibility.