How to differentiate different types of RAM?

For replacing or upgrading your desktop RAM, it’s very important to know what kind of RAM it is currently using. You can know that by reading the nameplate sticker sticked on it or looking physically. Every type of RAM operates in different voltage levels and frequency . Here inn this post we will discuss them one by one.

1. SDRAM. “Synchronous dynamic random-access memory”. It’s working frequency varies from 66MHz to 133MHz. It cames in 168 pin DIMM. It had a 64-bit bus, and worked at 3.3V. It was popular around middle 1990-early 2000.

2. DDR1. “Double data rate synchronous dynamic random-access memory” (DDR SDRAM). Its frequency varies from 100MHz to 400MHz. It has 184 pins DIMM. There were also some DDR1 with 433MHz launched for overclockers. It was sold with capacities from 128MB to 1GB. At servers you can also find DDR1 with 2GB per DIMM. It had a transfer rate from 1.6GB/s to 3.2GB/s, in single channel tp 3.2GB-6.4GB/s in dual channel, depending on frequency. It was powered at 2.5V.

DDR1 was used for socket Intel 478, Intel LGA 775, AMD Socket A, Socket 756, AMD Socket 939. DDR1 was popular since 1999 to 2005 approximately. Bandwidth was double that SDRAM had.

3. DDR2. “Double data rate synchronous dynamic random-access memory”. It came with 240 pins per DIMM. It’s frequency varies from 200MHz to 1066MHz (1333MHz could be also found for a short period of time). The most used frequencies are 667MHz and 800MHz. It was sold with capacities from 256MB to 4GB per DIMM. It was popular starting with 2005–2006 through around 2008–2010. DDR2 is compatible with Intel Socket LGA 775, and AMD Socket AM2, AM2+. It’s usual operating voltage was 1.8V.

4. DDR3. “Double data rate type three SDRAM (DDR3 SDRAM)”. Launched in 2007, it has a frequency range from 800MHz to 3200MHz. The most popular types were at 1333MHz, 1600MHz, 1866MHz and 2133MHz. It came also with 240 pins DIMM. DDR3 was manufactured with capacities from 1GB to 8GB per DIMM. It was popular starting with 2009, until in 2016, still sold in 2017. It is compatible with the Sockets Intel’s LGA1366, LGA775, LGA1156, LGA1155, LGA1150, LGA1151, LGA2011 and AMDs AM3, AM3+, FM1, FM2 FM2+, and AM1. DDR3 usually DIMMs work at 1.5V.

A variant of DDR3 pinto-pin compatible is DDR3L, which has a lower operating voltage, of 1.35V.

5. DDR4. “Double data rate fourth-generation synchronous dynamic random-access memory”. It has 288 pins DIMM. It’s frequency variate from 1600MHz to 4266MHz. Most popular are 2133MHz or higher. Capacities differs from 2GB to 16GB. It is compatible by now with Sockets Intel LGA 2011-E3, Intel LGA1151 and AMD AM4 (on the way to be launched). It works at 1.2V.

Also there can be observed that every type of ram is different in terms of pins and specifications, so they are not compatible nor interchangeable. For preventing installing wrong types of RAM in an another version of socket, or to install them in a wrong position engineers also provided them with that small holes, that differs from a type of RAM to another.

Each Ram slot is given a name such as DDR2, DDR3, and the most recent DDR4. Each of these slots will only accept memory of the same standard. For example a motherboard that has a memory standard of DDR3 will not accept DDR2 or DDR4 memory modules. To ensure memory of the incorrect standard is not installed on a motherboard that doesn’t run a certain memory, small notches have been placed in the memory at different locations as shown below.


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