Micron has posted a record fiscal Q4 and told investors it expects memory supply to be much tighter through fiscal 2027 and 2028. Buyers are already trading DDR4 and DDR5 server RDIMMs hard on practitioner forums. Here is what the numbers mean for server memory budgets, and which HPE SmartMemory part numbers map to which ProLiant generation.
Memory has been the loudest line item in server quotes all year, and this week it got a fresh data point. Micron reported its fiscal fourth quarter on 30 September, its own company page and its CEO's follow-up interview have been circulating across the infrastructure feeds we track, and at the same time the practitioner forums are full of people buying and selling server RDIMMs in volume: wanted posts for matched sets of 16GB DDR5 RDIMMs, and for-sale lots of 32GB DDR4-2666 and DDR4-3200 modules pulled from retired Gen10 and Gen10 Plus estates. The question buyers keep asking is simple: does it get cheaper if I wait, and which memory does my platform actually take?
What Micron reported
- Fiscal Q4 2026 (quarter ended 3 September 2026) revenue was $54.23bn, against $41.46bn in the prior quarter and $11.32bn a year earlier.
- Non-GAAP gross margin was 87.0%, up from 45.7% in the same quarter a year earlier.
- Full fiscal 2026 revenue was $133.19bn, against $37.38bn in fiscal 2025.
- The Core Data Center business unit took $18.0bn of quarterly revenue, up from $1.58bn a year earlier. Cloud Memory took $16.3bn, up from $4.5bn.
- Guidance for fiscal Q1 2027 is $61.5bn, plus or minus $1.5bn, at roughly 86% gross margin.
- On the earnings call, management said it expects memory and storage supply and demand to be much tighter in fiscal 2027 and 2028 than in 2026.
- On product, Micron is sampling 512GB DDR5 RDIMMs rated up to 9,200 MT/s and has completed customer qualifications of 8,800 MT/s server RDIMMs.
Read the margin line rather than the revenue line. A gross margin that moves from the mid-40s to 87% in twelve months is price, not just volume. That is the cost base every OEM memory kit is now built on.
What buyers are actually asking
- Should I fill all the slots now or buy the minimum and top up later? Operators on forums are splitting: some are buying full matched sets before the next price move, others are reusing DIMMs from decommissioned hosts.
- Can I reuse DDR4 from my Gen10 estate in a Gen10 Plus build? Sometimes, but the speed and rank rules differ by generation, so the part number matters more than the capacity.
- Is DDR5-4800 still worth buying when DDR5-6400 exists? For a Gen11 platform, usually yes: the platform sets the memory speed ceiling, so the right kit is the one listed in that server's QuickSpecs.
- Where has the secondary market gone? DDR4 RDIMM is now a traded commodity in its own right because it keeps whole Gen10 and Gen10 Plus fleets in service while DDR5 sits on allocation.
HPE SmartMemory part numbers by ProLiant generation
| Part number | Description | Platform fit |
|---|---|---|
| 815100-B21 | 32GB 2Rx4 DDR4-2666 CAS-19 RDIMM | Gen10 (1st Gen Xeon Scalable) |
| P00924-B21 | 32GB 2Rx4 DDR4-2933 CAS-21 RDIMM | Gen10 (2nd Gen Xeon Scalable) |
| P00930-B21 | 64GB 2Rx4 DDR4-2933 CAS-21 RDIMM | Gen10 (2nd Gen Xeon Scalable) |
| P06029-B21 | 16GB 1Rx4 DDR4-3200 CAS-22 RDIMM | Gen10 Plus (Intel) |
| P06033-B21 | 32GB 2Rx4 DDR4-3200 CAS-22 RDIMM | Gen10 Plus (Intel) |
| P06035-B21 | 64GB 2Rx4 DDR4-3200 CAS-22 RDIMM | Gen10 Plus (Intel) |
| P43322-B21 | 16GB 1Rx8 DDR5-4800 CAS-40 EC8 RDIMM | Gen11 (4th Gen Xeon Scalable) |
| P43328-B21 | 32GB 2Rx8 DDR5-4800 CAS-40 EC8 RDIMM | Gen11 (4th Gen Xeon Scalable) |
| P43331-B21 | 64GB 2Rx4 DDR5-4800 CAS-40 EC8 RDIMM | Gen11 (4th Gen Xeon Scalable) |
| P64706-B21 | 32GB 2Rx8 DDR5-5600 CAS-46 EC8 RDIMM | Gen11 (5th Gen Xeon Scalable) |
| P69727-B21 | 32GB 2Rx8 DDR5-6400 CAS-52 EC8 RDIMM | Current DDR5-6400 SmartMemory family |
| P69728-B21 | 64GB 2Rx4 DDR5-6400 CAS-52 EC8 RDIMM | Current DDR5-6400 SmartMemory family |
HPE publishes parallel kit families for some platforms (for example a separate DDR5-4800 P503xx family sits alongside the P433xx kits in the DDR5 QuickSpecs). Two kits with identical capacity, rank and speed are not always interchangeable across Intel and AMD ProLiant platforms, so match the part number, not just the label on the DIMM.
The ETON view
Our read: do not wait for memory to get cheaper on a project that has a date. The supplier with the clearest view of the market has told its own investors that supply gets tighter over the next two years, not looser, and its quarterly guidance points up again. Every OEM SmartMemory or Dell RDIMM kit price you are quoted sits on top of that.
What you can control is which memory you need. Price a Gen10 Plus or Gen11 build with tested pulled RDIMMs alongside new kits, because DDR4-3200 and DDR5-4800 modules come out of every estate that refreshes to a newer platform. Populate to the channel count the CPU needs for bandwidth, not to the maximum the board accepts, and plan capacity top-ups as a second purchase rather than over-buying today.
Keep the build vendor neutral. Lead time on a server is now often set by the DIMMs rather than the chassis, and a quote that ties memory to one OEM's allocation inherits that OEM's queue. We source HPE, Dell and generic RDIMMs, quote memory as its own line with its own lead time, and buy back DDR4 from decommissioned Gen10 and Gen10 Plus estates. With DRAM priced where it is, retired memory has real resale value, so put it on the refresh plan rather than in the skip.
Related infrastructure
- HPE Memory - RDIMM (registered ECC)
- Dell Memory - RDIMM (registered ECC)
- HPE Memory - LRDIMM (load reduced)
- HPE Rack Servers
- Dell PowerEdge Rack Servers
Category: Market · Vendor: Micron, HPE · Technology: DDR5 RDIMM, DDR4 RDIMM, HPE SmartMemory · Last verified: 02 Oct 2026 · ~5 min read
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