Refurbished server RAM: what's in the range and how to choose
Adding memory is usually the cheapest way to get more work out of a server you already own, and refurbished server RAM makes that sum even easier. This category covers ECC registered (RDIMM) and load-reduced (LRDIMM) modules in DDR4 and DDR3, from 8GB sticks for replacing a failed DIMM in an older host to 128GB modules for dense DDR4 platforms. The notes below explain how to read a module label, what has to match, and where capacity matters more than clock speed.
At a glance
- Generations
- DDR4 and DDR3 server memory in stock now. DDR5 is now becoming available in the refurbished market.
- Module types
- Registered ECC (RDIMM, an R on the label) and load-reduced ECC (LRDIMM, an L on the label). No unbuffered desktop memory.
- Capacities
- 8GB, 16GB, 32GB, 64GB and 128GB per module, plus kits such as 2x 16GB and 4x 16GB (64GB total).
- Ranks and organisation
- Single, dual and quad-rank modules built from x4 or x8 chips, including 1Rx4, 2Rx4, 2Rx8 and 4Rx4 parts.
- Speeds
- DDR4 from PC4-2133 up to PC4-2933; DDR3 from PC3-10600 up to PC3-14900.
- Manufacturers
- Hynix, Samsung and Micron modules, along with HPE-branded memory listed under its spares part number.
- Range and pricing
- 59 modules and kits currently in stock, priced from £5 to £1,000.
Matching memory to your server
Server RAM memory is built differently from the DDR4 RAM or DDR5 RAM sold for desktop PCs. Every module here is error-correcting and buffered, and most server boards that expect registered DIMMs will not train with unbuffered desktop sticks at all. Within server memory, compatibility comes down to a handful of details printed on every label.
- PC4 or PC3
- The DDR generation. PC4 is DDR4 and PC3 is DDR3. The two are keyed differently and physically will not fit each other's slots.
- Speed figure
- On DDR4 the number is the transfer rate, so 2666 means 2666 MT/s. DDR3 labels quote bandwidth instead: 10600 is DDR3-1333, 12800 is DDR3-1600 and 14900 is DDR3-1866.
- Letter suffix
- On DDR4 the first letter is the latency grade and the second is the buffer type, so 2666V-R is registered and 2933Y-L is load-reduced. On DDR3 the trailing R or L does the same job, as in 14900R versus 14900L.
- Rank and width
- 2Rx4 means two ranks built from x4 chips. Higher rank counts can limit how many modules a channel will run, or at what speed. Some platforms want x4 modules throughout to enable their advanced error-correction modes, so check before mixing x4 and x8.
A few population rules apply on almost every platform. Keep RDIMMs and LRDIMMs in separate servers rather than mixing them. Expect mixed speeds to run at the slowest module's rating, or lower if the CPU or the number of DIMMs per channel demands it. Fill channels evenly on each processor, ideally with identical modules, so the memory controller can interleave across all of them. Our explainer on RDIMM versus LRDIMM covers buffering and rank limits in more depth.
Before ordering, check your server vendor's memory population guide or qualified vendor list for the generation, buffer type and maximum ranks per channel it supports. Where a listing carries an OEM part number, such as P03055-091 or 647650-071, you can match it directly against the spares list for your model.
Typical deployments
Virtualisation hosts
Capacity limits how many VMs a host can carry long before memory clock speed does. 32GB and 64GB server RAM modules are the practical choice for DDR4 hosts: sixteen 32GB RDIMMs or eight 64GB LRDIMMs both take a host to 512GB of server RAM. Packing more memory into fewer hosts can also reduce the number of hypervisor licences you pay for. The Samsung 64GB PC4-2666V-L LRDIMM suits builds where density per slot matters more than the last few nanoseconds of latency.
SQL and database servers
Databases reward memory twice over. The buffer pool keeps hot data out of storage, and per-core licensing on engines such as SQL Server makes adding RAM far cheaper than adding cores. Choose fewer, faster cores, then populate every channel so bandwidth keeps pace. DDR4 32GB RDIMMs such as the Hynix 32GB 2666V-R (HMA84GR7CJR4N-VK) strike a sensible balance between capacity and speed per slot.
Storage and ZFS file servers
This is where ECC server memory earns its place. ZFS uses RAM as its read cache and trusts the data held in memory when it calculates checksums, so a silent bit flip is precisely what you want to avoid. File and backup servers rarely need fast memory; plenty of 16GB modules, such as the Samsung 16GB 2933Y-R RDIMM for DDR4 boxes or the Hynix 16GB PC3-14900R for DDR3, give a generous cache at modest cost.
In-memory analytics and scale-up workloads
Large caches, analytics engines and scale-up databases need the biggest modules a platform will accept, because the slot count is fixed. 128GB server RAM in LRDIMM form, such as the HPE 128GB 2933Y-L module (P03055-091), doubles what each slot holds compared with 64GB. Confirm your CPU's maximum memory per socket before planning a build around them.
Keeping DDR3 hosts in service
DDR3 server RAM makes topping up an older host an inexpensive stopgap while a refresh is planned. Single modules such as the Hynix 8GB PC3-10600R (647650-071) are ideal for replacing a failed DIMM like for like. Where the platform supports LRDIMMs, quad-rank parts like the Samsung 32GB PC3-14900L push a single slot to 32GB. Speeds on these platforms often drop as you add DIMMs per channel, so plan for capacity first.
Labs, test clusters and refreshes
Matched kits take the guesswork out of a test build or a like-for-like rebuild. The 64GB kit of four Hynix 16GB PC4-2133P RDIMMs fills four channels on one processor with identical modules. When an upgrade leaves you with a drawer of smaller DIMMs, our sell your used hardware page is the place to find out what they are worth.
Why buy server RAM from Compuwyze
- Memory modules and kits carry a 12-month return-to-base warranty.
- We aim to ship orders for simple items placed before 2pm the same day.
- Free UK delivery on orders over £50, normally arriving the next working day once shipped.
- International delivery through FedEx economy and priority services, usually within 2 to 5 days.
- Returns accepted within 30 days, with return shipping paid by the customer.
- Prefer a complete system: configured servers built through our build-to-order server configurator aim to ship within 2 business days and come with a 3-year return-to-base warranty.
Server RAM FAQs
What is the difference between server RAM and regular RAM?
Usually two things. Server modules are ECC, carrying extra bits that let the memory controller detect and correct single-bit errors as they happen. Most are also registered or load-reduced, with a buffer between the controller and the DRAM chips that allows a server to run many more modules per channel than a desktop board. Regular desktop DDR4 RAM is normally unbuffered and non-ECC, which keeps cost and latency down but gives up that protection.
Will server RAM work in a desktop PC, or desktop RAM in a server?
Generally not. Registered and load-reduced DIMMs need a board and memory controller built to drive them, which consumer desktop platforms are not. In the other direction, servers designed for RDIMMs will not run unbuffered desktop sticks. Some workstations and entry-level servers use unbuffered ECC modules instead, so check the board specification for which type it expects.
How much RAM does a server need?
Work back from the workload. For a hypervisor, total the memory allocated to each VM, then add headroom for the host itself and for taking over VMs if a partner host fails. A database server wants enough to hold its working set in memory. A small file server or domain controller may sit comfortably on 32GB to 64GB, while a busy virtualisation host can justify 256GB, 512GB or more. If you are specifying a whole machine, our guide on choosing a server for a small business walks through sizing.
How much does 32GB of server RAM cost?
Generation, speed and buffer type affect the price as much as capacity does, so a 32GB DDR3 LRDIMM and a 32GB DDR4-2666 RDIMM are priced quite differently. Filter the listings above by capacity and generation to compare current 32GB server memory side by side.
Can I mix different memory modules in one server?
Within limits. Never mix DDR generations, and keep RDIMMs and LRDIMMs apart. Many platforms tolerate different capacities or rank counts, but doing so can unbalance channels and reduce bandwidth, and mixed speeds will run at the slowest module's rating. Identical modules in every populated channel is the safest approach, which is why matched kits are worth considering.
Do you sell DDR5 server memory?
We have a DDR5 memory category, but no DDR5 modules are in stock at the moment. DDR5 RDIMMs are used by the newest server platforms only, and they will not fit DDR4 or DDR3 slots. Our current range is DDR4 and DDR3 ECC memory.