LRDIMM (load-reduced DIMM)
LRDIMMs put a buffer between the memory chips and the memory controller, so the controller sees one electrical load per module regardless of rank count. That is what lets a server reach terabytes of RAM at full speed when it is fully populated.
They cost more per gigabyte and you cannot mix LRDIMMs with RDIMMs in the same system. Choose them when the workload needs the capacity, such as large SQL Server instances, in-memory analytics or dense virtualization hosts.
At a glance
| Generations | DDR3 LRDIMM, DDR4 LRDIMM (64 to 256 GB), DDR5 uses 3DS RDIMMs instead |
|---|---|
| Typical capacities | 64, 128, 256 GB per module |
| Rule | Never mix LRDIMM and RDIMM in one server |
| Platforms | PowerEdge R730/R740/R750/R940, ThinkSystem SR650/SR850/SR950, Supermicro X10/X11/X12 |
What RackLedge does
- Capacity planning for SAP HANA, SQL Server and large VM hosts
- Full-population speed validation (LRDIMMs hold speed where 3DPC RDIMMs drop)
- Vendor part-number cross-reference to avoid unqualified modules
How we work
A memory engagement starts with evidence, not a parts list. We pull utilization from your monitoring or hypervisor, confirm memory is the real constraint, and only then choose modules that keep every channel populated at full speed.
Firmware comes first. BIOS and BMC updates fix memory training bugs and unlock newer module types, so we baseline them before opening the chassis. Installation is scheduled in a maintenance window and validated with a memory test and an application check before the server goes back into rotation.
Parts are new or tested refurbished with a warranty, matched to the vendor's qualified list or an equivalent specification, and we keep a record of exactly what went where so the next upgrade starts from documentation rather than guesswork.
Related services
More on server memory
Frequently asked questions
Do DDR5 servers use LRDIMMs?
Mostly no. DDR5 high-capacity modules are 3DS RDIMMs. LRDIMMs matter for DDR4 systems that need 1 TB or more.
Are LRDIMMs slower?
Latency is marginally higher because of the buffer, but at full population they are faster than RDIMMs because they do not force the bus down a speed grade.
Need a hand with this?
Tell us what you are running and what is slowing you down. You get a straight assessment and a plan, with no obligation. Support desk is staffed 24/7.