DDR SDRAM is a faster form of SDRAM used as the main working memory in Pentium III or higher computers. It belongs to the DIMM architecture family and comes in single or double-sided chip configurations. DDR RAM passes data using both rising and falling edges of the system clock, making it twice as fast as SDRAM. DDR3 is the most expensive and least common type. DDR memory uses less power and operates at 2.5V. DDR2 modules cannot replace DDR RAM, and the memory used is determined by the motherboard chipset.
Double data rate synchronous dynamic random access memory, or DDR SDRAM for short, is a type of computer memory used in Pentium III or higher computers. DDR RAM is the computer’s main working memory, storing program instructions and data for use by the central processing unit (CPU) through the bus controller. DDR memory belongs to the dual in-line memory module (DIMM) architecture family and is a faster form of SDRAM.
Each DDR memory module has a notch on the connection side and two notches on the side that attach to latches on the PC’s motherboard to hold it in place. DDR RAM can come in single-sided or double-sided chip configurations. Desktop DDR has 184 pins, compared to 168 pins on SDRAM. The laptop versions, called SO-DIMMs, contain 200 pins.
There are three main types of ddr ram. DDR or DDR1, has clock speeds ranging from 100Mhz up to 200Mhz. 2-pin DDR240 replaces DDR1 and quadruples the speed of SDRAM, peaking at 266 MHz. DDR3, a 240-pin module, uses less power and transfers data eight times faster than SDRAM. DDR3 is also the most expensive and least common of the ddr memory types.
One of the main differences between SDRAM and ddr memory is how it uses the clock signal in data exchanges. SDRAM transfers 64 bits of data at a time to the CPU using the rising edge of a clock signal. In contrast, ddr ram passes data using both the rising and falling edges of the system clock with no change to the clock rate. This means that up to 128 bits can be transferred at any given time, making it twice as fast as SDRAM. The faster the data exchange method, the more performance is improved.
To determine the maximum bandwidth of this type of computer memory, multiply the memory bus clock by the number of channels: 1 for SDRAM, 2 for DDR, 4 for DDR2, and 8 for DDR3, and 64, the number of bits transferred. Then divide the product by 8, the number of bits per byte.
Therefore, for a motherboard with a minimum bus frequency of 100, the peak transfer rate would be 1600 Megabytes per second (MB/s). For computers using a 133 MHz bus, the peak is reduced to 2100 MB/s (DDR-266 or PC-2100). Finally, a DDR2 module with a clock speed of 266 Mhz peaks at 8500 MB/s.
The standard memory module names also incorporate bandwidth measurements. DDR-200 or PC-1600 relates to a DDR1 module with a clock speed of 100 MHz and a transfer rate of 1600 MB/s. DDR2-400 or PC2-3200 similarly refers to a DDR2 module with a clock speed of 100 MHz and a transfer rate of 3200 MB/s.
In addition to speed, ddr memory also uses less power than SDRAM, operating at 2.5V (2.6V for DDR-400) compared to 3.3V for SDRAM. A spin-off of DDR for mobile devices, called MDDR, uses a significantly lower voltage than desktop ddr memory.
Unfortunately, ddr memory is not backwards compatible with older forms of memory. Therefore, DDR2 modules cannot replace DDR RAM. In fact, the computer memory used is determined by the chipset of the motherboard, and not all motherboards support higher speeds. It’s best to consult your motherboard or PC manual for specifics before performing a memory upgrade.
Protect your devices with Threat Protection by NordVPN
