Memory is one of the least expensive parts of a server to change and one of the easiest to get wrong at scale. A refresh across a rack or a cluster needs more than a part number: you have to know what each server holds today, what its processor generation allows, and how to keep the number of distinct parts small. This guide sets out the steps we see work for data center, hosting and IT teams. It applies across Dell PowerEdge, HPE ProLiant, Lenovo ThinkSystem, Cisco UCS, Supermicro and the other makers in the data center memory hub.
Step 1: Take inventory
List every server model and the number of units. For each model, read what is installed. On Linux:
sudo dmidecode -t memory
This prints each slot with its Size, Speed, Type (DDR4 or DDR5), Locator and Part Number. On Windows Server, use PowerShell:
Get-CimInstance Win32_PhysicalMemory | Select-Object BankLabel, Capacity, Speed, PartNumber
The management controller on most servers (iDRAC, iLO, XClarity or a generic BMC) also reports installed modules without logging in to the operating system. Run the check on one server per model, then confirm the rest by comparing the total capacity in your asset system.
Step 2: Identify the platform generation
The processor generation sets the memory generation, the number of channels and the top speed.
| Platform | Memory (top speed) | Channels per socket |
|---|---|---|
| Intel Xeon E5 v3 and v4 | DDR4-2133 and 2400 | 4 |
| Intel Xeon Scalable, 1st and 2nd Gen | DDR4-2666 and 2933 | 6 |
| Intel Xeon Scalable, 3rd Gen | DDR4-3200 | 8 |
| Intel Xeon Scalable, 4th and 5th Gen | DDR5-4800 and 5600 | 8 |
| AMD EPYC 7001, 7002 and 7003 | DDR4-2666 and 3200 | 8 |
| AMD EPYC 9004 | DDR5-4800 | 12 |
| AMD EPYC 9005 and Intel Xeon 6 | DDR5-6400 | Varies by model |
Your server's own specification governs. Check the listing for your exact model on the hub page, which states the supported speed, slot count and maximum capacity.
Step 3: Decide what to do with each model
For each server model there are three options: add modules to empty slots, replace smaller modules with larger ones, or leave the machine as it is and plan its retirement. Memory upgrades suit servers whose processors and storage are still adequate but that run out of memory headroom. Before upgrading a very old platform, weigh the age of the hardware and the support you have left.
Step 4: Choose RDIMM or LRDIMM
Most servers use ECC RDIMM. LRDIMM is used where the platform supports it and more memory per channel is needed. A server takes one type, never a mix. Entry servers and single-socket workstation boards often take ECC UDIMM. The listing for your server states which.
Step 5: Populate evenly and keep modules matched
- Fill channels evenly. Leaving a channel empty reduces bandwidth even if capacity is adequate.
- Use identical modules within a server: same size, speed and rank.
- Follow the maker's slot order. Slot order is in the server's manual and in each NEMIX listing.
- On many platforms, using two modules per channel lowers the top speed compared with one. The processor and population determine the final speed, which may be lower than the module rating.
Step 6: Standardize the part list
A mixed estate of 20 server models often needs only a handful of module part numbers. A single DDR4-3200 RDIMM may serve several models of the same generation. Send us the inventory and we return the matching module for each model and the shortest list that covers them all. If your records hold OEM part numbers, use the part-number collections for HPE, Dell, Cisco and Lenovo.
Step 7: Plan spares
Keep a small stock of each part number you standardize on. A failed module is then a swap, not a procurement cycle. NEMIX-brand modules carry a lifetime warranty; register your purchase to record it.
Step 8: Pilot, then roll out
Upgrade one server of each model. Confirm it posts, that the management controller and operating system report the new capacity, and that it passes your normal burn-in or memory test. Then order the full quantity and roll out in batches, recording the new configuration in your asset system.
Step 9: Retire and recover
Keep removed modules together by model. When whole servers are retired, NEMIX RAM also offers IT asset disposition.
Where to start in the catalog
Go to the data center and server memory hub. Brand guides: HPE, Dell, Lenovo ThinkSystem, Cisco UCS, Supermicro, GIGABYTE, Fujitsu PRIMERGY and motherboard memory by chipset. For desktops and laptops, read the fleet memory upgrade guide.
Ordering for a data center
Researched, matched, and compatibility-tested by NEMIX RAM, a US-based server memory specialist since 1993, and backed by a lifetime warranty. Purchase orders, net terms and volume pricing are available for businesses, hosting providers, schools and government buyers. Request a quote with your server list, or see the education and government page for supplier details. NEMIX RAM is an independent memory supplier and is not affiliated with the server makers named in this guide; their names are trademarks of their owners, used only to identify compatible systems.
Frequently asked questions
Can I mix RDIMM and LRDIMM in the same server?
No. A server takes one type. Check the listing for your model to see whether it uses RDIMM or LRDIMM.
Can I mix DDR4 and DDR5 modules?
No. A server supports one generation, and DDR4 and DDR5 modules are keyed differently and do not fit each other's slots.
What happens if I mix module speeds?
The memory runs at the speed the processor and slot population support, and a mix generally runs at the slowest module's speed. For predictable results, use identical modules in a server.
Why populate every memory channel?
Each channel adds bandwidth. A server with some channels left empty gives up bandwidth even if total capacity looks right, so install modules evenly across channels.
How do I find the part numbers on installed modules?
On Linux, run sudo dmidecode -t memory. On Windows, use the PowerShell command in this guide. Out-of-band tools such as iDRAC, iLO, XClarity or the BMC web page also list installed modules.
Do you work from purchase orders and net terms?
Yes. Purchase orders, net terms for approved credit applications and volume pricing are available. Use the quote form to start.