Tech Talk
Types of DRAM Modules
Last updated 12 December 2024
As you select DRAM memory for your servers, systems, or devices, the variety of options can feel overwhelming. Right now, there are four common types of DRAM (Dynamic Random Access Memory), with the most recent to join the party - CUDIMMs - alongside RDIMMs, SODIMMs, and UDIMMs. The modules are each tailored and built for specific use cases and systems. Our job at Simms is to help you understand them better to help you select and source them, so let's try do that for you with a breakdown of each.
UDIMMs (Unbuffered DIMMs)
UDIMMs are DRAM memory modules that simply don't have a buffer or register between the DRAM chips and the memory controller. The lack of buffering makes them faster but limits things like scalability, especially in multi-module setups.
Key Features
- Speed: We'll come onto RDIMMs soon, but generally UDIMMs are faster than this type of module as there is no buffer adding latency.
- Power: Comparing to RDIMMs again, they tend to use less power.
- Supported: Compared to others, UDIMMs are widely supported.
Where you may find them used
- Desktop PCs.
- Workstations.
- Entry-level servers or consumer-grade server systems.
RDIMMs (Register DIMMs)
Unlike UDIMMs, RDIMMs include a register (or a buffer). These are placed between the DRAM chips and the memory controller on the module. Why the register? Well, it is there to stabilise the system. It reduces the load and allows the larger memory configurations, thus increasing reliability.
Key Features:
- Scalability: RDIMMs support higher capacities than that of UDIMMs.
- Stability: As mentioned above, the register allows for a more stable performance - better for systems with high memory density.
- Latency: Important for the below use cases, they have better latency benefits compared to UDIMMs.
Where you may find them used
- Data centres.
- Servers.
- Mission-critical systems.
SODIMMs (Small Outline DIMMs)
SODIMMs are built for devices and systems where space comes at a premium. The limited space need means SODIMMs are created compact, meaning they'll maximise efficiency. They offer similar performance to that of standard DIMMs. They're the go-to for portable systems.
Key Features:
- Size: As above, at about 50% that size wise compared to other DIMMs.
- Capacity: Due to the size, they are available in smaller capacities to that for full-sized DIMMs.
- Performance: Optimised for space efficiency, the performance is still on par with UDIMMs for example.
Where you may find them used
- Embedded systems.
- Laptops.
- Mini PCs.
CUDIMMs (Clocked Unbuffered DIMMs)
As of writing this article, these are fairly new to market and are designed to handle the demanding workloads that largely come with gaming. CUDIMMs are built for higher bandwidth, with the potential to go over 9,000MT/s. What's more, for overlocking these modules are built for it - perfect for gaming.
Key Features:
- Clock speeds: Higher frequencies compared to UDIMMs.
- Signal Integrity: Designed to improve this with a clock driver on the DIMM module.
- Stability: Better stability and reliability at high memory gaming speeds.
Where you may find them used
- Gaming.
Summary
| Type | Best use | Pros |
| UDIMM | Consumer, workplace, entry-level servers | Low latent, well supported |
| RDIMM | Data centres, server builders, mission-critical | High capacities, stable |
| SODIMM | Industrial, embedded, small form-factor devices | Compact, portable |
| CUDIMM | Gaming | Signal integrity, higher frequencies |
Choosing the right memory for you
At Simms, we help select, source, and understand the right memory modules for your requirements. Hopefully this article has allowed you to understand the strengths and pitfalls of different types of DRAM memory modules to help you make an informed decision to ensure your system and/or devices perform to the best.
If it hasn't and you need more help, or wish to discuss the brands we have available to deliver the above types of DRAM memory for you, contact Simms today.