Cisco UCS Server Memory: C-Series, B-Series & X-Series by Server and Part Number
Memory upgrades for Cisco UCS C-Series rack servers, B-Series blade servers and X-Series compute nodes, from M5 to M8. Listings are matched either to one UCS server model or to one Cisco memory part number (PID), using the memory type, speed and module sizes Cisco specifies. This page explains how to identify your Cisco UCS system and which memory it takes. To go straight to the products, type your Cisco UCS model or part number into the search bar at the top of the page.
Find your Cisco UCS model first
The server model (for example UCS C220 M6 or UCS X210c M7) is on the front pull-out tab and the system label, and in Cisco Intersight or UCS Manager. Cisco memory part numbers start with UCS-M, for example UCS-MRX64G2RE3; they are on your Cisco quote and on the installed module label.
Shop Cisco UCS memory
| Cisco UCS family | Covers | Memory | Listings |
|---|---|---|---|
| Cisco UCS servers | Every UCS server listing, M5 to M8 | DDR4, DDR5 · RDIMM, LRDIMM | 50 |
| DDR5 UCS servers (M7, M8) | C220, C240, C225, C245, X210c, X215c and other M7 and M8 systems | DDR5 · RDIMM | 40 |
| DDR4 UCS servers (M5, M6) | C220, C240, C480, B200, X210c M6 and other M5 and M6 systems | DDR4 · RDIMM, LRDIMM | 66 |
| Cisco LRDIMM | Load-reduced modules for high-capacity M5 and M6 builds | DDR4, DDR3 · LRDIMM | 30 |
| Cisco part numbers | Memory matched to a Cisco PID such as UCS-MRX64G2RE3 | DDR4, DDR5, DDR3 · RDIMM, LRDIMM | 60 |
Which memory does my UCS server take?
- M8 (Intel Xeon 6, AMD EPYC 9004/9005): DDR5-6400 RDIMM.
- M7 (4th and 5th Gen Intel Xeon Scalable): DDR5-4800 or DDR5-5600 RDIMM, depending on the processor.
- M6 (3rd Gen Intel Xeon Scalable, AMD EPYC 7003): DDR4-3200 RDIMM or LRDIMM.
- M5 (1st and 2nd Gen Intel Xeon Scalable): DDR4-2933 RDIMM or LRDIMM; 1st Gen processors run memory at 2666 MT/s.
Rules that apply across Cisco UCS systems
- Registered or unbuffered, never both. Servers built on Xeon Scalable, Xeon 6, Xeon W-2400/3400 and AMD EPYC take registered memory (RDIMM or LRDIMM); entry servers on Xeon E, Xeon 6300, EPYC 4004 and similar take ECC unbuffered UDIMMs. Each listing names the type its system takes.
- Do not mix RDIMMs with LRDIMMs, or 3DS with standard RDIMMs, in the same system.
- Fill memory channels in matched groups of identical modules: six or eight per processor on Intel Xeon Scalable and Xeon 6, eight or twelve on AMD EPYC.
- Match the generation. DDR5, DDR4 and DDR3 modules are keyed differently and will not fit each other's slots.
- Speed follows the platform. Faster modules clock down automatically to the speed the processor and slot population support.
Ordering by Cisco part number
Cisco sells memory under PIDs such as UCS-MRX64G2RE3 or UCS-ML-128G4RW. If you are adding to modules you already have or ordering from a Cisco quote, search the PID or browse Cisco part numbers. Each part-number listing is matched to the density, rank and speed of the original module.
Why NEMIX RAM for Cisco UCS memory
NEMIX RAM is a US-based server memory specialist, in business since 1993. Every module is researched, matched, and compatibility-tested by NEMIX RAM, is JEDEC-compliant, and is backed by a lifetime warranty. Each Cisco UCS listing names the exact model or part number it fits, so there is no guesswork about module type, speed or capacity.
Data centers and Cisco partners
Purchase orders, net terms and volume pricing are available for data centers, enterprises, government buyers, Cisco partners and resellers. Request a quote for a full UCS domain or a spares pool, or send us your model or part number and we will confirm the right module before you order.
Frequently asked
Can I mix NEMIX RAM with the Cisco memory already installed?
Yes, if the new modules match the installed ones in type, capacity, rank and speed. Cisco recommends identical modules within each memory channel group; when in doubt, send us the PID of the installed modules.
Will DDR5 memory work in my M6 server?
No. M5 and M6 servers take DDR4; M7 and M8 servers take DDR5. The modules are physically different.
Should I choose RDIMM or LRDIMM?
Match the type already installed: Cisco does not support mixing RDIMMs and LRDIMMs. LRDIMMs suit the highest-capacity M5 and M6 builds.
NEMIX RAM can deliver any Configuration your Fleet Requires
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