RAM Rank vs. Channel: How Do They Impact Performance?

If you’re looking for a quick fix for boosting the performance of your computer, upgrading its RAM is usually the first step.

However, there is so much more to upgrading your memory than slamming in additional RAM. Did you know the RAM rank and even the number of channels can make a significant difference in the performance of your memory?

In this article, we break down the differences between RAM rank and channel and explain why they’re both worth considering when upgrading your RAM.

What is RAM Rank?

RAM rank refers to how the RAM memory cells are arranged within a memory module.

Each rank of RAM comprises a set of memory chips that can be accessed for read/write memory functions at the same time. A RAM module may comprise multiple ranks of RAM which can only be accessed sequentially as the memory controller can only deal with one rank at a time.

The RAM ranks that are commercially available include:

• Single-rank
• Dual-rank
• Quad-rank and 
• Octo-rank

JEDEC, the trade body of the semiconductor industry, devised the RAM rank system.

This systematized approach to memory structure standardizes the number and configuration of memory cells carried on each module of RAM. It applies to all types, form factors, and applications of RAM with each memory rank being 64 or 72-bits wide.

Prior to the rank system, the number of individual memory chips carried did not consistently correspond with memory rank, with modules being described as single-sided or double-sided.

Manufacturers display the RAM rank on the labeling of every memory module. The rank is identified by the letters Rx, preceded by 1 for single-rank, 2 for dual rank, 4 for quad-rank, or 8 for octo-rank. The amount of memory in gigabytes follows the ‘Rx.’ For example, an 8GB single-rank Ram is written as 1Rx8. 

What is the RAM channel?

The RAM channel refers to an aspect of memory architecture called the memory channel. This is the number of channels of communication available between a RAM module and the memory controller. 

The memory controller is the digital circuitry that manages the flow of data to and from the RAM module. Its ability to access individual RAM ranks and cells is a rate-limiting factor for RAM speed and performance. Multichannel memory architecture increases the number of channels the memory controller can use, producing an uplift in the data transfer rate. 

You can upgrade the RAM channel from a single channel, which only has one channel for communication between the memory controller and the RAM to:

• Dual-channel RAM 
• Triple-channel RAM
• Quad-channel RAM
• Hexa-channel RAM
• Octa-channel RAM

Adding more RAM channels roughly multiplies the data rate by the number of channels available. Dual-channel RAM has existed since at least the 1960s and is featured in early IBM computers.

What’s the Difference Between RAM Rank and Channel?

Memory rank and memory channel are two completely different aspects of RAM memory architecture. The rank of the RAM is concerned with the number of sets of memory chips the module contains. The memory channels of the RAM enable the memory controller to access the various ranks of RAM, providing a data conduit between the RAM and the CPU.

Each rank of RAM has a 64-bit wide interface for the exchange of data. Increasing the number of channels increases the number of interfaces for sending data from the RAM ranks simultaneously per CPU clock cycle. 

By increasing the number of channels from single to dual channel, the number of 64-bit interfaces for data transfer have doubled. This means that you can read double the amount of data per second. In addition, the data interleaves between the two channels for even greater speed and consistency of performance. 

It’s important to remember that the additional channels need to be populated with RAM or they will add zero benefits to the performance of your computer. Form quad channel systems require 4 memory modules to work optimally. 

As you can see, memory rank and channel work together to achieve a tangible uplift in memory performance, which may exceed a simple increase in the total amount of RAM. 

RAM Rank vs. Channel: A Side-by-Side Comparison

Similarities and Differences

Similarities

• RAM rank and RAM channel are both concerned with random access memory, the volatile working memory of a computer. 
• The ranks of RAM and the RAM channels are on the motherboard.
• Both aspects of RAM use integrated circuits and semiconductor technology.

Differences

• RAM rank relates to the arrangement of memory chips within a RAM module.
• RAM channels are communication circuits between a RAM module and the memory controller.
• The memory controller can only access individual ranks of RAM at a time.
• Interleaving is used to speed up access to multiple ranks of RAM.
• Increasing the number of channels increases the rate at which data exchange with RAM and the memory controller can take place. 
• The number of available RAM slots does not correlate with the number of memory channels.

What Are RAM Ranks Used For? 

RAM ranks arrange the memory cells that are used as the computer’s short-term memory. The individual rows of memory cells hold working data and temporary files required by the operating system (OS), browsers, and programs run on the computer.

Memory rank affects the configuration and performance of RAM in three ways:

1. Memory rank affects how the computer accesses data that is held in the memory. Each processor and memory channel has a maximum number of ranks that can be accessed‌. If the number of ranks in the RAM slots exceeds the capacity of the RAM channels, memory controller, or processor, the computer may become slower or cannot operate correctly. 
2. The data bit width of the memory is fixed, so manufacturers create multiple memory ranks to make their RAM modules memory dense. High-capacity RAM modules of 16GB or more can have up to four ranks per module.
3. Error Correction Code memory chips have additional bits that aid the correction of single or multiple-bit errors. ECC memory increases the width of a rank of RAM from 64 to 72 bits.

RAM Rank vs. Channel: Which One Should Be Upgraded?

You can increase the speed and performance of a computer by increasing the number of RAM ranks or increasing the number of memory channels available.

A step up from single-rank to dual or quad-rank RAM increases the memory density of the RAM module while increasing the number of channels boosts the bandwidth available for data exchange. An upgrade from single-rank to dual-rank RAM is usually cost-effective and your computer will run faster because of the interleaving of the two ranks of memory. 

However, there is only so much uplift you can achieve without upgrading the number of memory channels available to the RAM for faster data transfer. This is because with increasing numbers of ranks come various administrative processes that can eventually slow things down.

If your choices are limited, increasing the number of memory channels is the better investment. This is is because you’re increasing the number of high-speed conduits for data exchange, enabling simultaneous access to data from multiple ranks or whole modules. 

RAM Rank vs. Channel: 6 Must-Know Facts

• Most modern motherboards have between two and four memory channels.
• CPUs only support a fixed number of memory channels in line with the number of memory channels integrated on the motherboard.
• Multi-rank RAM and multi-channel RAM use interleaving to enhance performance
• The IC chips that make up the memory module can vary in their individual capacity. They are usually 8-bit or 4-bit.
• Manufacturers can spread out a single rank of RAM over both sides of a RAM module. Only the RAM sticker can tell you the rank of the RAM.
• To install RAM successfully, ensure that the memory modules you install have matching specifications like capacity, speed, latency, and rank. 

Final Thoughts

It’s clear that there is so much more to selecting a RAM module than its size.

By considering the RAM rank and channel, you can increase the memory density and speed at which data is accessed and transferred from the RAM module.

With RAM rank vs. channel, paying attention to both is good, but maximizing the number of channels available to the memory controller is the best investment for a more marked improvement in performance.  

Up Next…

Interested in more computing-related comparisons? Click the links below:

• Unified Memory vs. RAM: How Do They Compare? One is a volatile form of memory, the other, is non-volatile. Discover other features they possess which set them apart and the more efficient of the two.
• RAM vs. Cache: What’s the Difference?  They are both forms of volatile memory used to speed up a CPU’s performance. Yet one is measured in gigabytes and the other in bytes. Find out which is which and other key differences between them both.
• SDRAM vs. RAM: What’s the Difference? One is synchronous, and the other, is asynchronous. What other key differences exist between them? Find out here.