Lenovo 4X77A90966 is the exact ordering identifier covered here, in the ThinkSystem range. The reviewed specification records capacity: 64GB; type: DDR5 RDIMM; speed: 6400MHz. Use this guide to decide what to include in a configuration request, rather than treating similar model numbers as interchangeable.
Specifications that define this model
The values below retain the source qualifiers. A missing field is not evidence that a capability is included or absent.
| Specification | Recorded value |
|---|---|
| Capacity | 64GB |
| Type | DDR5 RDIMM |
| Speed | 6400MHz |
| Rank | 2Rx4 |
| Fits | ThinkSystem SR650 V4 |
How to evaluate this exact configuration
Module capacity
Module capacity for 4X77A90966: 64GB. Calculate the intended total capacity from module quantity, then check the platform's population rules. Module capacity is not the server's maximum memory capacity.
Memory technology
Memory technology for 4X77A90966: DDR5 RDIMM. Match the documented memory technology and organisation. A physically similar module, another generation or a different ordering suffix is not automatically an interchangeable part.
Module speed rating
Module speed rating for 4X77A90966: 6400MHz. Check the installed processor and DIMM population. The module's printed rating does not establish the operating speed of a populated server.
Documented platform scope
Documented platform scope for 4X77A90966: ThinkSystem SR650 V4. Check the exact generation, processor, installed memory and population sequence against the manufacturer configuration guide. A platform listing is not approval for every configuration within that family.
Compare nearby ordering codes
| Model | Capacity | Rank | Type |
|---|---|---|---|
| 4X77A90966 | 64GB | 2Rx4 | DDR5 RDIMM |
| 4X77A90963 | 16GB | 1Rx8 | DDR5 RDIMM |
| 4X77A90964 | 32GB | 1Rx4 | DDR5 RDIMM |
These are specification comparisons, not statements that the models are drop-in replacements. Compare the configuration limits before choosing an alternative.
4X77A90963 manufacturer reference · 4X77A90964 manufacturer reference
Questions before you request a quote
Which product does 4X77A90966 identify?
It identifies Lenovo ThinkSystem TruDDR5 64GB 6400MHz 2Rx4 RDIMM. Keep 4X77A90966 on the requirement and quote; a family name alone does not fix the ordering configuration.
What compatibility scope is recorded for 4X77A90966?
The recorded scope is ThinkSystem SR650 V4. Confirm the exact machine generation and configuration in the manufacturer guide; this is not a blanket compatibility promise.
What should I check before ordering 4X77A90966?
Start with the specification and configuration checks above, then state the quantity, destination and intended connections or platform. Ask for the exact contents of the offered configuration and identify every proposed substitution separately.
Build a clear requirement
Specify 4X77A90966, quantity and delivery country, then add the configuration information discussed above. Keep accessories and any accepted alternative as separate lines. Request current pricing and availability rather than relying on an article for live commercial information.
View the 4X77A90966 product listing · Browse Lenovo memory · Request a quote
For the wider selection process, read the related buying guide.
Sources and scope
Document and identifier checks: 2026-10-17. Prepared from manufacturer documentation and the catalogue's recorded specifications; no hands-on benchmark is claimed. Confirm destination-specific options and configuration eligibility against the source documents. Prices, stock, delivery dates and coverage terms are not established by this guide.