Unbuffered RAM vs. Buffered RAM: What’s the Difference?

Flash memory vs RAM

Unbuffered RAM vs. Buffered RAM: What’s the Difference?

Random access memory (RAM) is a fast-evolving and diverse technology with many types and formats to choose from.

Unbuffered RAM vs. buffered RAM describes the absence or presence of a registry between the RAM and a computer’s memory controller. Opinions are divided over how much difference this registry makes to the speed and performance of the RAM, and few people even know how to tell the difference between the two. 

In this article, we’ll share the most important differences between unbuffered RAM and buffered RAM, explain what these two types of RAM are, and evaluate which one is best for your computing application.

Computer RAM sticks on a black background

Buffered and unbuffered memory cannot be mixed

What is Unbuffered RAM?

Unbuffered RAM or unregistered memory is the conventional memory format that has direct connectivity between the RAM module and the computer’s memory controller. It differs from registered, or buffered, RAM which carries a register between the memory and the memory controller. 

Unbuffered RAM is the common, cheaper RAM format found in PCs and laptops which don’t have the added production costs, energy, and circuitry of buffered RAM. Access to the memory is faster as the RAM does not have the added step of cycling through a registry, but unbuffered RAM is generally less stable. 

A Quick History of Unbuffered RAM

This is the conventional memory that has developed over almost 80 years. It has transitioned from mechanical counters to high-speed, volatile circuits.

The earliest form of RAM was a cathode ray tube known as the Williams–Kilburn tube that stored data as charged spots. The invention of the integrated circuit massively advanced the development of RAM by Robert Noyce, the founder of Intel. Later, the synchronization of RAM with the CPU clock produced massive accelerations in the speed of computing.

Key Types of Unbuffered RAM

Unbuffered RAM comes in a variety of form factors and formats. The two main types of unbuffered RAM are:

  • Dynamic RAM: stores its data bit by bit in individual memory cells. Each memory cell is manufactured using metal-oxide-semiconductor (MOS) technology and comprises transistors and capacitors. Dynamic RAM is the most common form of unbuffered RAM. It is extremely diverse with leading RAM types that include Synchronous Dynamic Random-Access Memory (SDRAM), Double Data Rate Synchronous Dynamic Random-Access Memory (DDR SDRAM), and Error Correction Code (ECC DRAM).
  • Static RAM: an alternate form of RAM that uses latching circuitry to store data. It doesn’t consume as much power as dynamic RAM and it doesn’t have to be periodically refreshed. However, though static Ram is volatile, it can retain data after power has been removed. The absence of a refresh circuit makes static RAM much more simple than dynamic RAM.

What is Buffered RAM?

Buffered RAM, or registered memory, is RAM that has an integrated register or buffer that sits between the RAM modules and the computer’s memory controller.

Dual In-line Memory Modules (DIMM) that are buffered are known as RDIMM, versus standard, unregistered modules that are called UDIMM or DIMM. This arrangement has high stability with a smaller electrical load on the memory controller than in an unbuffered arrangement. 

Buffered memory costs more than unregistered RAM, due to its additional circuitry. It is a high-specification memory type that is used in applications that require scalable storage and robust data management, such as servers. Buffered memory often includes Error Correcting Code memory for additional robustness.

How Does Buffered RAM Work?

The creation of a register or buffer provides a space where data can be pre-loaded for use by the CPU. It acts as a store that can compensate for the difference in transfer speeds between the RAM and the memory controller. The register can accumulate data received from the memory controller or RAM for use when required.

Close up of microATX motherboard MS-6390 with an AMD Athlon processor in a Socket 462 slot
Your computer’s motherboard must be compatible with its RAM type.

The Purpose of Buffered RAM

Buffered RAM has two key functions which provide added robustness and data integrity:

Data Restoration

If needed, the memory buffer unit can restore data that has deteriorated as it travels through the bus architecture. This protects against the effects of data corruption in real-time.

Preemptive Error Checking

The addition of a buffer provides a space where error-checking can take place on data moving into and out of the RAM. Not all buffered RAM is error-correcting code RAM, but all buffered RAM can complete this function. 

A disadvantage of these functions is the introduction of latency to the RAM, which usually operates with extremely low latency. This delay slows the RAM down, as all memory has to pass through this buffer.

The added functionality of buffered RAM also leads to greater power consumption than a standard unbuffered module and requires a socket that is set at a higher voltage level than conventional RAM. The buffer also generates additional heat that can age the module prematurely. Motherboards that accept buffered RAM are usually specifically configured with additional ventilation and cooling. 

What’s the Difference Between Unbuffered RAM and Buffered RAM?

Though both these forms of memory act as short-term, working memory storage in a computer, buffered RAM and unbuffered RAM differ in their composition and function. Here are the key differences you need to know:

  • Buffered RAM contains a register or buffer that sits between the memory and the memory controller. The registry usually comprises flip-flop or latch circuitry that can read and write bits of data and also acts as an interface between the RAM and the memory controller.
  • Unbuffered RAM is register-free and directly connects to the CPU via the front side bus. This RAM format has a direct conduit for data exchange rather than relying on a buffer.
  • Buffered RAM usually runs one clock cycle behind an equivalent unbuffered RAM module. This is because the RAM is buffered for one clock cycle between the memory bus and the RAM.
  • Unbuffered RAM is more prevalent than buffered RAM. It is cheaper and used in personal computing. Buffered RAM is used in applications that require high levels of data integrity, such as servers and any system that requires a stable operating environment. 

Unbuffered RAM vs. Buffered RAM: A Side-by-Side Comparison

Unbuffered RAMBuffered RAM
What it isMemory chipMemory chip
Primary UseStorage of temporary system filesStorage of temporary system files with an additional registry
Initial Release1940s1990s
Influential DevelopersFreddie Williams and Tom KilburnApple
Technologies InfluencedDRAM, SRAM, RDRAM, DDR SDRAM, and VRAMPower Macintosh computers, servers, high-spec workstations

Similarities and Differences


  • Unbuffered and buffered RAM are types of volatile memory.
  • A memory controller controls both unbuffered and buffered RAM.
  • The CPU uses both forms of RAM for the storage of temporary files and operating system applications.


  • Buffered memory contains a buffer/registry between the memory and the memory controller. 
  • Buffered RAM is usually slower than unbuffered RAM.
  • Buffered RAM is more expensive than unbuffered RAM.
  • Buffered RAM is used in applications that require enhanced data integrity like servers.

What is Buffered RAM Used for?

The error checking and data restoration properties of buffered RAM make buffered RAM a key type of server RAM. It reduces the electrical load on the memory controller and has high data stability, making it advantageous as server RAM.

Buffered memory, also called registered memory, is used to reduce the electrical load on the memory controller. Besides, buffered RAM is usually used for servers and other high-end systems that need a stable operating environment, because it has high stability in stored data.

There are three types of buffered RAM used in servers:

  1. Registered memory (RDIMM): this form of buffered RAM carries registers that buffer the signals between the RAM and the memory controller.
  2. Local reduced memory (LRDIMM): a newer, more powerful, and lower latency form of buffered memory that can support large memory capacities. It primarily uses its buffer to manage the electrical load associated with the high memory density.
  3. Fully buffered memory (FBDIMM): an older buffered RAM format that is predominantly used in servers enhances the speed and stability of the server memory

Does Unbuffered RAM Need to Be Upgraded?

Buffered memory slows the memory speed in applications like personal computing, business computing, and gaming, so it does not need to be installed on most computers. The motherboard also has to be fully compatible with buffered RAM because of its power consumption and the heat it generates.

VRAM vs. RAM: 6 Must-Know Facts

  • Unbuffered RAM is the type of RAM that is used in PC and laptops.
  • Buffered RAM only works in a motherboard that accommodates it, as the motherboard must match the memory type. 
  • Buffered and unbuffered memory cannot be mixed.
  • The registers on the buffered RAM module support the use of multiple dual-rank DIMMs per memory channel. This increases the amount of memory that the server or workstation can support.
  • Apple Power Macintosh computers mainly used buffered RAM in the 1990s until the release of the G3 and G4 series computers.
  • The movement of data through the register of buffered RAM costs a clock cycle which drops the latency of the RAM. However, a faster RAM module might overcome the latency increase.

Final Thoughts

If you are looking for a RAM upgrade for your PC, buffered RAM is not only unnecessary but may also slow your computer down. It is unlikely that a regular motherboard would be compatible with this form of RAM. Using unbuffered RAM is a cheap, efficient, and low-latency option for personal computing. 


Frequently Asked Questions

What is ECC memory?

Error Correcting Code memory can check itself for errors and correct them. This technology eradicates single-bit data errors and enhances the stability of the stored data. ECC buffered RAM is used in critical data storage applications, including industrial and infrastructural databases.

What is CAS latency?

CAS stands for Column Address Strobe, a type of latency in computing where there is a day of a certain number of clock cycles between a READ command and the availability of the requested data.

How can you tell if RAM is buffered?

It is not always easy to tell if RAM is buffered or unbuffered, but the labeling of the RAM stick may carry an ‘R’ for buffered and ‘U’ for unbuffered. You can also tell if RAM is buffered by looking at the leads next to the first notch of the RAM module. In buffered memory, the leads are evenly spaced.

Do Macs use buffered RAM?

Early Macs (1990s) used to use buffered RAM, but most contemporary Macs use unbuffered RAM.

Is it worth upgrading my unbuffered RAM?

Upgrading your PC RAM is one of the most convenient ways to improve the performance of your computer. It is beneficial if you work with large files or run multiple applications simultaneously.

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