What Is DDR SDRAM?

Before you can understand what DDR SDRAM is, you must first understand the basics of RAM and how it works. RAM stands for random access memory and is basically how fast your computer runs. Newer computers, especially ones that run with Vista, have extra RAM so that your computer can run smoothly and at faster speeds than older computers. RAM is the location of all essential files that are currently being used. RAM may include the operating system and other files and programs that you are currently using. RAM is faster than ROM, Read Only Memory, but where as ROM is semi-permanent, RAM data is lost whenever you reboot your computer.

DDR vs SDR

DDR SDRAM doubles the data rate that is used in SDR SDRAM (Single Data Rate Synchronous Dynamic Random Access Memory) by transferring data on both sides of the clock symbol rather than just one. Also, DDR SDRAM uses higher frequencies while also lowering the amount of voltage required. Higher frequencies allow for higher amounts of data to be transferred at once while lower voltages create less heat, allow for longer battery life, and even aids in compacting memory storage into smaller devices.

DDR SDRAM Sizes

1 GB

A 1 GB DDR SDRAM chip is the largest amount of memory that DDR SDRAM currently supports. As many computers now require massive amounts of RAM to run large, high-quality applications, most newer computers are equipped with two 1 GB DDR SDRAM chips.

512 MB

A 512 MB DDR SDRAM chip is the second largest amount of memory that DDR SDRAM currently supports. 512 MB chips are usually bundled in pairs so that a computer may have access to 1 GB of RAM. 512 MB chips used to be the standard amount of RAM for a computer to have and are still found in older computer.

256 MB

A 256 MB DDR SDRAM chip is the third largest amount of memory that DDR SDRAM currently supports. A single 256 MB chip would not be enough memory to run a modern computer as just one large program may use up 256 MB of memory. In computers that have 256 MB chips, there is often two chips of this size to allow for up to 512 MB of memory to be used.

128 MB

A 128 MB DDR SDRAM chip is the fourth largest amount of memory that DDR SDRAM currently supports. DDR SDRAM chips do not come in smaller forms than the 128 MB chip. 128 MB chips come in pairs to give the user 256 MB of memory, although 256 MB doesn’t provide enough memory for a modern computer. 128 MB chips were only used in very old computers that did not require as much memory.

DDR SDRAM Speeds

The following items are speeds that different models of DDR SDRAM can exhibit, ranked from newest to oldest.

PC3200

PC3200 DDR is the highest speed that DDR SDRAM currently supports. PC3200 DDR is used in faster machines and is usually coupled with 1 GB DDR SDRAM memory chips. A PC3200 runs on a frequency of 200 Mhz.

PC2700

PC2700 DDR is the second highest speed that DDR SDRAM currently supports. PC2700 DDR is used in slightly older generations such as the Windows 2008 and Windows 2003 models. PC2700 is usually coupled with 512 MB DDR SDRAM memory chips. A PC2700 runs on a frequency of 166 Mhz.

PC2100

PC2100 DDR is the third highest speed that DDR SDRAM currently supports. PC2100 DDR is found in much older machines and is usually coupled with 256 MB DDR SDRAM memory chips. A PC2100 runs on a frequency of 133 Mhz.

PC1600

PC1600 DDR is the fourth highest speed that DDR SDRAM currently supports. There is no slower DDR SDRAM chip than the PC1600. This speed is usually found in 128 MB DDR SDRAM memory chips. A PC1600 runs on a frequency of 100 Mhz.