Unified Memory vs. RAM: How Do They Compare?

Key Points

• Random access memory is only capable of storing memory as long as power is supplied, unified memory on the other hand is capable of storing it in the absence of a power supply.
• RAM has been developed for around seven decades as opposed to unified memory which was developed during the previous decade.
• It is possible to upgrade RAM, however, it is not possible to upgrade unified memory.

Unified memory is a modern memory technology that combines RAM and a hard drive into a single memory pool. This newer approach, favored by Apple Inc., is thought to improve computing efficiency and energy consumption, usually coming at a premium. 

So, is unified memory a great idea or just a cynical marketing ploy? Does regular RAM still have something to offer?

Read on for a full comparison of unified memory and RAM, where we’ll break down the two and explain their differences so you can evaluate which is the better choice for your computing needs.

Let’s get started!

What is Unified Memory?

Unified memory is a memory technology where access to the computer’s entire memory resource (short- and long-term) is shared between all the processing components of the computer.

This means that the CPU and GPU share memory locations rather than having distinct RAM allocations and types. With no discrete memory pools, there is no need for VRAM as the GPU is also integrated. This unified approach applies to all the device’s physical memory locations.

Apple is one of the leading advocates of this system-on-a-chip (SoC) approach. The M1, released in late 2020, is one of the most advanced examples of “Unified Memory Architecture” (UMA). The RAM of this custom-designed ARM-based processor is shared as a pooled memory resource that any processing component can access. 

With UMA, the GPU or CPU can increase their use of system memory whenever needed. Other parts of the SoC are ramped down in response. A fabric controller allocates the M1 memory between the various cores without dedicating specific portions of memory to individual SoC components. Processor components have free access to the same memory addresses to acquire the data that they need. 

Nvidia, the creator of the GPU, also developed its own version of unified memory. CUDA 6, released in 2013, pooled and shared managed memory between the GPU and CPU with a single shared pointer.

It’s easy to see how this arrangement boosts efficiency and performance. There is no need to shuttle portions of data between the RAM and VRAM as all memory is instantly accessible. Apple is confident that its UMA delivers more responsive computing, with enhanced graphics and gaming performance because of the increased availability utility of the memory. 

What is RAM?

Random access memory (RAM) is a semiconductor technology that provides computing devices with fast, volatile memory required for the storage of temporary files. It’s usually found on the motherboard, near the CPU socket in Small Outline Dual In-line Memory Module (SODIMM) slots. 

RAM technology developed over 70 years, contributing to massive advancements in the processing speeds and performance of computers. It is the main memory format for most personal computing applications and provides faster read and write functionality than other storage components, like a hard-disk drive or optical drive. 

RAM is a short-term memory store and will only hold data within its circuits as long as there is power. It is the memory component needed for immediate working and can transfer data to longer-term storage when required. 

RAM comes in a variety of types and formats and is synchronized with the system clock. Synchronized dynamic RAM (SDRAM) is a contemporary RAM type that is in widespread use with several generations of double data rate (DDR) technology that delivers enhanced speed. VRAM is a dedicated RAM format that can meet the technical demands of GPUs for improved performance of graphics applications.

What’s the Difference Between Unified Memory and RAM?

The most significant differences between unified memory and RAM are in its format and characteristics, location, access, and use.

Still scratching your head? Here are eight key differences between unified memory and conventional RAM setups:

Format

Since 2000, the main format for RAM has been the DDR generations of Dual In-line Memory Module (DIMM). These RAM sticks comprise multiple memory cells mounted on a PCB. JEDEC, the semiconductor trade organization standardizes DIMM, which comes in a range of form factors and sizes suitable for either PC or laptop use.

With unified memory like Apple’s M1, the RAM is integrated into the SoC. It is provided as unified memory modules of up to 64GB in size, rather than distinct system memory and GPU memory.

Volatility

RAM is volatile memory and will be wiped if it loses power. Though unified memory can be accessed and used like RAM, it is non-volatile and will store its data without supplied power. This means that your data is fully protected in the event of an outage or other interruption in system power.

Relationship with CPU

RAM provides the system memory that is used by the CPU to hold the temporary files and data it needs to carry out its operations. The RAM can process data quickly, providing the working memory programs and applications needed, while storing data generated by work that is being performed. 

The CPU in a unified memory system accesses pooled memory resources. It has a much larger amount of memory it can use to perform operations more efficiently. As the hard-disk drive memory is integrated, the acquisition and use of data become intuitive and efficient.

Relationship with GPU

GPUs carry their own dedicated memory known as visual RAM (VRAM). This special allocation of RAM is necessary to support demanding graphics applications like design software and gaming. VRAM is configured to ensure that graphics and video are correctly mapped and displayed.

In a unified memory SoC, the GPU accesses the pooled RAM and can ramp up its memory use beyond the capacity of a VRAM module. This enhances GPU performance significantly, making unified memory worth considering for gaming and advanced design software applications. 

Capacity

System RAM and visual RAM capacity are determined by the size of the RAM module supplied. Upgrading RAM and increasing memory capacity can deliver increases in processing speed and performance. However, to increase the amount of memory available to the GPU, a whole new GPU card would be required with a larger amount of integrated VRAM. 

Because unified memory has a pooled memory resource, the GPU and CPU can simply acquire more memory when needed. The pooled memory size needs to support all processor components generously for smooth, fast performance that can cope with increases in demand. A specific size of RAM module does not limit them.

Speed

For programs to operate efficiently, they need to have adequate space to store their temporary files and data. A lack of RAM or high RAM consumption can therefore slow down your computer.

Unified memory’s pooled memory provides room for increased memory consumption by any processor component. It has a higher bandwidth bus, making the flow of data to the CPU much, much faster. It also bypasses the delays that come with dealing with a hard drive.

Overall, communication between all participating components and the pooled memory is faster, producing a desirable uptick in speed.

Unified Memory vs. RAM: A Side-by-Side Comparison

Similarities and Differences

Similarities

• You can use both conventional RAM and unified memory for short-term memory storage.
• Unified Memory can fulfill the role of VRAM for a GPU.
• The CPU can use RAM and unified memory for its working data and temporary files.

Differences

• Unified memory is non-volatile; RAM is volatile.
• Unified memory can store the data held on an HDD or SSD along with the data that RAM would hold.
• Unified memory is pooled for access by the GPU and CPU; RAM either serves the CPU or GPU.
• RAM is only short-term data; unified memory can store data long-term.
• RAM is removable; unified memory is fully integrated as part of an SoC.
• RAM can be upgraded; unified memory cannot be upgraded.

What is Unified Memory Used For?

Unlike RAM, unified memory takes on all the data storage of the computer system, both short- and long-term.

This pooled memory resource is non-volatile and capable of storing data for as long as a hard drive or another long-term storage module. However, it can also behave like RAM and provide the fast, readily accessible short-term data storage that the operating system and software programs rely on for efficient functioning. 

Does RAM Need to Be Upgraded to Unified Memory? 

Though Unified Memory architecture has existed for at least a decade, it is not widely adopted by computer manufacturers. Apple’s M1 SoC has brought unified memory into the mainstream and showed the excellent performance that unified memory can deliver. 

Unified memory not only increases the speed and performance of a computer but also cuts down on the energy consumption of both RAM modules and an HDD, which can be significant. As it is non-volatile, you have the reassurance that data is stored even if the power is removed.

The major downside of unified memory, like most hardware, is the price. Unified memory is not only a different and newer type of memory, it is also integrated with other hardware components like the CPU, so you are going to pay much more in relative cost compared to a simple upgrade of RAM size or technology.

Right now, owning a Mac or MacBook with an M1 chip is going to be the fastest way to get to grips with this new memory technology. 

Unified Memory vs. RAM: 6 Must-Know Facts

• In June 2022, Apple released the M2 chip. This is a successor SoC to the M1 Chip and features Unified Memory Architecture. 
• Unified Memory Architecture can achieve 3.9x faster video processing and 7.1x faster image process than if conventional VRAM is used.
• A shared pool of managed memory facilitates simpler programming as developers and engineers don’t need to repeatedly allocate and copy device memory. 
• Freddie Williams and Tom Kilburn invented the earliest form of RAM, the Williams-Kilburn Tube. This cathode ray tube stored data as dots on a grid within the tube. 
• Contemporary RAM contains multiple multiplexing and demultiplexing circuits that form data lines to the addressed storage for reading and writing entries.
• RAM can be read or written in any order.

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