Server RAM Buying Guide: DDR4 vs DDR5 ECC for Dell HP Lenovo
Everything you need to know about buying server memory in 2026. RDIMM vs LRDIMM, DDR4 vs DDR5, and exact compatibility for Dell PowerEdge, HP ProLiant, and Lenovo ThinkSystem.
The Server Memory Landscape in 2026
Server memory procurement is deceptively complicated. You cannot just buy "64GB of RAM" and drop it in. You need the right generation (DDR4 or DDR5), the right type (RDIMM or LRDIMM), the right speed grade, and the right rank configuration --- and all of it has to match what your server platform actually supports. Get any one of those wrong and the server either refuses to boot or runs at degraded speed.
This guide walks through every decision point and gives you specific part numbers you can search on Pro Disk Network to order the right memory for your Dell, HP, or Lenovo servers.
DDR4 vs DDR5: Which Generation Do You Need
This is not a preference question. Your server platform dictates which generation you use.
DDR4 Platforms (still widely deployed):
- Dell PowerEdge R740, R740xd, R640, R440, T440
- Dell PowerEdge R750, R650 (12th Gen Intel, DDR4 only)
- HP ProLiant DL380 Gen10, DL360 Gen10, DL380 Gen10 Plus
- Lenovo ThinkSystem SR650, SR630, SR550
DDR5 Platforms (current generation):
- Dell PowerEdge R760, R660, R860, T560 (14th Gen Intel / AMD EPYC 9004)
- HP ProLiant DL380a Gen11, DL360 Gen11, DL380 Gen11
- Lenovo ThinkSystem SR650 V3, SR630 V3
Key Takeaway: If your server shipped in 2022 or earlier, it almost certainly uses DDR4. Servers from late 2022 onward may use DDR5. Check your server's data sheet or run dmidecode -t memory on Linux to confirm.
RDIMM vs LRDIMM: Picking the Right Type
| Feature | RDIMM | LRDIMM |
|---|---|---|
| Full name | Registered DIMM | Load-Reduced DIMM |
| Max capacity per module | 64GB (DDR4), 128GB (DDR5) | 128GB (DDR4), 256GB (DDR5) |
| Cost per GB | Lower | 15-25% premium |
| Speed at 2 DPC | Full rated speed | Full rated speed |
| Best for | General purpose, VMs, web servers | Large memory pools, databases, SAP HANA |
Pro Tip: For most deployments, RDIMM is the right choice. You only need LRDIMM when you require more than 64GB per slot (DDR4) or 128GB per slot (DDR5). Mixing RDIMM and LRDIMM in the same server is not supported and will prevent POST.
DDR4 ECC RDIMM: Part Numbers and Pricing
Here are the specific modules we ship most often for DDR4 servers, broken down by capacity:
8GB DDR4-2666 RDIMM
| Brand | Part Number | Speed | Rank | Price |
|---|---|---|---|---|
| Samsung | M393A1G43EB1-CTD | 2666 MT/s | 1Rx8 | $12 - $18 |
| SK Hynix | HMA81GR7CJR8N-VK | 2666 MT/s | 1Rx8 | $10 - $16 |
| Micron | MTA9ASF1G72PZ-2G6 | 2666 MT/s | 1Rx8 | $10 - $15 |
16GB DDR4-2933 RDIMM
| Brand | Part Number | Speed | Rank | Price |
|---|---|---|---|---|
| Samsung | M393A2K43DB3-CVF | 2933 MT/s | 2Rx8 | $22 - $32 |
| SK Hynix | HMA82GR7DJR8N-XN | 2933 MT/s | 2Rx8 | $20 - $30 |
| Micron | MTA18ASF2G72PDZ-2G9 | 2933 MT/s | 2Rx8 | $18 - $28 |
32GB DDR4-3200 RDIMM
| Brand | Part Number | Speed | Rank | Price |
|---|---|---|---|---|
| Samsung | M393A4K40EB3-CWE | 3200 MT/s | 2Rx4 | $38 - $55 |
| SK Hynix | HMA84GR7DJR4N-XN | 3200 MT/s | 2Rx4 | $35 - $50 |
| Micron | MTA36ASF4G72PZ-3G2 | 3200 MT/s | 2Rx4 | $32 - $48 |
64GB DDR4-3200 RDIMM
| Brand | Part Number | Speed | Rank | Price |
|---|---|---|---|---|
| Samsung | M393A8G40AB2-CWE | 3200 MT/s | 2Rx4 | $85 - $120 |
| SK Hynix | HMAA8GR7AJR4N-XN | 3200 MT/s | 2Rx4 | $80 - $110 |
| Micron | MTA36ASF8G72PZ-3G2 | 3200 MT/s | 2Rx4 | $75 - $105 |
128GB DDR4-3200 LRDIMM (for high-capacity builds)
| Brand | Part Number | Speed | Rank | Price |
|---|---|---|---|---|
| Samsung | M386AAG40AM3-CWE | 3200 MT/s | 4DRx4 | $240 - $340 |
| SK Hynix | HMABAGL7ABR4N-XN | 3200 MT/s | 4DRx4 | $220 - $310 |
Search DDR4 ECC RDIMM for our complete DDR4 server memory inventory.
DDR5 ECC RDIMM: Part Numbers and Pricing
32GB DDR5-4800 RDIMM
| Brand | Part Number | Speed | Price |
|---|---|---|---|
| Samsung | M393A4G43BB4-CWE | 4800 MT/s | $55 - $75 |
| SK Hynix | HMCG84AEBRA109N | 4800 MT/s | $50 - $70 |
| Micron | MTC20F2046S1RC48BA1 | 4800 MT/s | $48 - $68 |
64GB DDR5-5600 RDIMM
| Brand | Part Number | Speed | Price |
|---|---|---|---|
| Samsung | M393A8G40CB4-CWE | 5600 MT/s | $130 - $170 |
| SK Hynix | HMCG94AEBRA109N | 5600 MT/s | $120 - $160 |
| Micron | MTC40F2046S1RC48BA1 | 5600 MT/s | $115 - $155 |
128GB DDR5-4800 RDIMM
| Brand | Part Number | Speed | Price |
|---|---|---|---|
| Samsung | M393AAG40M32-CAECO | 4800 MT/s | $340 - $420 |
| Micron | MTC80F2046S1RC48BA1 | 4800 MT/s | $310 - $390 |
Server Compatibility Quick Reference
Dell PowerEdge:
- R740/R640: DDR4-2933 RDIMM, 24 DIMM slots (12 per CPU), max 1.5TB with 64GB modules
- R750/R650: DDR4-3200 RDIMM, 32 DIMM slots (16 per CPU), max 2TB with 64GB modules
- R760/R660: DDR5-4800/5600 RDIMM, 32 DIMM slots, max 4TB with 128GB modules
HP ProLiant:
- DL380 Gen10: DDR4-2933 RDIMM, 24 DIMM slots, max 1.5TB
- DL380 Gen10 Plus: DDR4-3200 RDIMM, 32 DIMM slots, max 2TB
- DL380 Gen11: DDR5-4800 RDIMM, 32 DIMM slots, max 4TB
Lenovo ThinkSystem:
- SR650/SR630: DDR4-2933 RDIMM, 24 DIMM slots, max 1.5TB
- SR650 V3/SR630 V3: DDR5-4800 RDIMM, 32 DIMM slots, max 4TB
Common Mistakes to Avoid
- Mixing speeds --- Installing DDR4-2666 alongside DDR4-3200 forces all DIMMs to run at 2666. Buy matching speed grades.
- Ignoring rank count --- Populating 2 DPC with quad-rank LRDIMMs on some Intel platforms drops speed by two bins. Check your CPU's memory population matrix.
- Buying unbuffered ECC --- UDIMM ECC is for workstations, not servers. Servers require Registered (RDIMM) or Load-Reduced (LRDIMM) modules.
- Skipping BIOS updates --- Both Dell and HP release BIOS updates that add support for newer memory part numbers. Always update BIOS before installing new DIMMs.
How to Order
Search by part number on Pro Disk Network for exact pricing and availability. We stock all three major brands (Samsung, SK Hynix, Micron) across every capacity tier. Volume pricing is available for orders of 12+ modules --- email sales@prodisknetwork.com with your server model and target configuration for a same-day quote.