Everything you need to know about Random Access Memory
In its simplest form, RAM (Random Access Memory) is a type of computer memory, often called short-term memory because it is volatile, meaning the data is not saved when the power is turned off.
When business users turn on the computer, the operating system and applications are loaded into the computer’s RAM, which is connected directly to the CPU, making the data quickly accessible for processing.
In enterprise environments, RAM (memory modules) comes in different shapes and sizes. DIMM (Dual In-Line Memory Module) can be found on desktops, workstations and servers, while laptops require a smaller physical SODIMM (Small Outline DIMM).
A memory module contains several DRAM (Dynamic RAM) chips, a type of semiconductor memory. Dynamic simply means that the data held by transistors in the chips is constantly being refreshed. The number of DRAM chips on a memory module varies depending on its capacity (8 GB, 16 GB, 32 GB).
The lithography of DRAM chips has been revised and improved many times over the past few decades, leading not only to reductions in cost per bit, but also to reducing component size and increasing clock speed. Overall, DRAM now delivers faster performance and higher capacities, but uses less power, which reduces energy costs, controls heat, and extends battery life.
DRAM operates in one of two modes: synchronous or asynchronous. Asynchronous was the common DRAM technology used until the late 1990s. Synchronous mode means that read, write, and refresh operations are controlled by a system clock, in sync with the clock speed of a computer’s CPU. Today’s computers use synchronous mode, or Synchronous Random Access Memory (SDRAM), which connects to the motherboard via a memory module.
DRAM Business Manager, Kingston EMEA.
New generations of DRAM
The latest version of SDRAM is DDR5 (Double Data Rate 5th Generation), which comes in a range of standard speeds starting at 4800M/Ts (mega transfers per second) and is an indicator of the speed at which data is transferred to and from the computer. memory module. Roughly every seven years, a new generation of memory is introduced, designed to meet the ever-increasing demands for speed, density and configurations in enterprise computing environments. For example, DDR5 is designed with new features that deliver higher performance, lower power, and more robust data integrity for the next decade of computing. It debuted in 2021.
IT decision makers considering purchasing memory should be aware that memory modules are not backward compatible. DDR5 memory does not physically fit into a DDR4 or DDR3 memory socket. Within a memory generation, higher speeds are backward compatible. For example, if a user purchases a standard DDR5–5600MT/s module and uses it with a 12th generation Intel processor, the speed memory is automatically ‘clocked’ to run at 4800M/Ts, the speed supported by the host system or lower . This depends on the CPU model and the number of memory modules installed in the system.
Knowing which processor and motherboard are already installed in the computer is essential if you plan to expand the memory, but there are also some other considerations. Most PCs have four RAM sockets, some, such as workstations, have as many as eight, but laptops are likely to have only two accessible memory sockets, and in thin models it may be as few as one.
Different types of RAM
Although they may look the same and perform the same function, the type of memory module in HEDT (High-End Desktop) and servers is different from that in PCs. Intel Xeon and the AMD Epyc series of server CPUs come with a higher number of CPU cores and more memory channels compared to Intel Core and AMD Ryzen desktop CPUs. Therefore, RAM specifications and features for servers differ from those for PCs.
Server CPUs require a registered DIMM that supports the ECC (Error Correcting Code) function, which allows correcting bit errors on the memory bus (between the memory controller and the DRAM chip), ensuring data integrity. RDC (Registered Clock Driver) is an additional component found on RDIMM and not present on Unbuffered DIMM (UDIMM), and ensures that all components on the memory module operate at the same clock cycle, keeping the system stable when a high number of modules are installed.
The type of memory module made for desktops and laptops is generally non-ECC unbuffered DIMM. The data processed by users on these types of systems is considered less critical than the data processed by servers that, for example, host websites or handle online transactional processing, and which must respect specific SLAs (Service Level Agreements) and up-times . 99.9999% 24/7. Non-ECC UDIMMs contain fewer components and features than RDIMMs and are therefore more affordable while remaining a reliable memory solution. Unbuffered types of RAM exist in both DIMM and SODIMM form factors.
Improve performance
RAM memory is mainly sold in individual modules, but is also available in sets of two, four or eight, ranging in capacity from 4 GB for DDR3 to 96 GB for DDR5 (in single modules) and up to 256 GB in sets (256 GB is only offered as a kit of 8 in DDR4 and DDR 5). The configurations are consistent with the memory channel architecture and, if installed correctly, can provide a major performance boost. To give an example of the performance potential, upgrading a DDR5-4800MT/s module with a peak bandwidth of 38.4 GB/s to a dual-channel setup immediately expands the bandwidth to 76.8 GB/s .
Accelerated speed
Users with industry standard speeds are limited to what their computer’s processor and motherboard support, especially if modules cannot be installed in a second memory bank. On a dual-channel, four-socket motherboard, these are arranged in two memory banks, with each memory channel having two sockets. If a DDR5 user can install modules in a second bank, in most cases the memory can be forced to clock down to a lower speed to account for limitations within the processor.
Users looking for a big boost, such as gamers, can opt for overclockable memory. This can be done safely using Intel XMP and AMD EXPO profiles, but professional help is advisable. Selecting the right gaming memory for overclocking a system means deciding on price versus speed versus capacity, the potential limitations of motherboards and processors, and RGB versus non-RGB (to take advantage of lighting).
Useful glossary
In addition to the acronyms we already explained above, here are some additional terms that are useful to know:
CPU – Central processing units are the core of the computer.
PMIC – Power Management Integrated circuits help regulate the power required by the memory module components. For server class modules, the PMIC uses 12V; for PC class modules it uses 5V.
SPD hub – DDR5 uses a new device that integrates the Serial Presence Detect EEPROM with additional functions, manages access to the external controller and decouples the memory load on the internal bus from the external one.
ECC dying – Error correction code that reduces the risk of data leakage by correcting errors in the chip, increasing reliability and reducing the number of defects.
2-channel, 4-channel, 8-channel – Single RAM modules – dual channel, quad channel, octal channel.
MHz – MHz is an abbreviation of megahertz and means one million cycles per second, or one million hertz. This unit of frequency measurement is used to indicate the speed at which data moves within and between components.
MT/s is an abbreviation for megatransfers (or million transfers) per second and is a more accurate measurement for the effective data rate (speed) of DDR SDRAM memory in computers.
Non-binary memory – The density of DRAM chips usually doubles with each iteration, but with DDR5 an intermediate density – 24 Gbit – was introduced, which offers more flexibility and is called non-binary memory.
GB/sec – Gigabytes per second. A Gigabyte is a unit of data storage capacity of approximately 1 billion bytes. It has been a common unit of capacity measurement for data storage products since the mid-1980s.
Clutch!
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