Most small and mid-sized companies end up choosing between two rack servers from the same family: a 1U model and its 2U sibling. Dell sells the PowerEdge R660 (1U) next to the R760 (2U); HPE sells the ProLiant DL360 Gen11 (1U) next to the DL380 Gen11 (2U). They share processors and management, so the real question is what the extra 1U of height buys you. This guide answers that with facts taken only from the vendors' own technical guides and user guides, then gives a simple way to decide.
Before you start
- List what the server must hold in three years, not just on day one: number and type of drives, PCIe cards (NICs, HBAs, GPUs) and memory.
- Check rack space, power and cooling where the server will live. See server room power, cooling and UPS basics.
- Figures below are maximum documented options for each chassis. A given configuration (controller, riser, number of processors) can reduce them; confirm against the guide for the exact model you order.
What the documentation says: Dell R660 vs R760
Both come from the Dell technical guides (June 2026 editions).
| Item | R660 (1U) | R760 (2U) |
|---|---|---|
| Height | 42.8 mm | 86.8 mm |
| Front drive options | Up to 10 x 2.5-inch SAS/SATA/NVMe, or 8 x 2.5-inch NVMe, or 14 or 16 x EDSFF E3.S; no 3.5-inch option listed | Up to 12 x 3.5-inch SAS/SATA, or 24, 16 or 8 x 2.5-inch, or up to 16 x EDSFF E3.S |
| Rear drive options | Up to 2 x 2.5-inch or 2 x E3.S | 2 or 4 x 2.5-inch, or 4 x E3.S |
| PCIe slots | Up to three (2 x Gen5 or 3 x Gen4) | Up to 8 x Gen4 or up to 4 x Gen5 |
| GPU options | Up to 3 x 75 W single-wide | Up to two double-wide 350 W, or six single-wide 75 W |
| Memory | 32 DDR5 DIMM slots | 32 DDR5 DIMM slots |
| Fans | Up to 4 sets of dual-fan hot-plug modules; N+1 fan redundancy | Up to six hot-swap fans; N+1 fan redundancy |
| Power supplies | Two redundant AC or DC power supply units on both | |
What the documentation says: HPE DL360 vs DL380 Gen11
These come from the HPE user guides' component and specification pages.
| Item | DL360 Gen11 (1U) | DL380 Gen11 (2U) |
|---|---|---|
| Height | 4.29 cm | 8.75 cm |
| Front drive layouts | EDSFF, SFF (8 SFF backplane; the media bay can be replaced by 2 SFF bays) or LFF (4 LFF backplane) | SFF in up to three 8 SFF boxes, 12 LFF, or 8 LFF with an optional 2 SFF; rear and midplane drive boxes are also listed |
| Rear expansion | PCIe5 slots 1 to 3 (slot 3 requires the second processor), plus OCP 3.0 slots 14 and 15 | Primary riser slots 1 to 3, secondary 4 to 6, tertiary 7 to 8, plus OCP slots 14 and 15 |
| GPU | GPU in the primary riser cage; above 75 W needs the riser power cable | Accelerator or GPU in the primary, secondary or tertiary position; high-performance heatsinks required |
| Weight (max) | 21 kg SFF, 22 kg LFF | 33 kg SFF, 37 kg LFF |
Memory is the same on the two Dell models (32 DIMM slots each), so on these pairs memory alone is rarely the reason to move to 2U. Population rules matter more than slot count: see PowerEdge memory population rules and ProLiant memory population rules.
Step 1 — Decide by storage
- Need large-capacity 3.5-inch (LFF) drives, for example a file server or backup target? On Dell, the R660 lists no 3.5-inch option while the R760 takes up to 12. On HPE, the DL360 takes 4 LFF and the DL380 takes 12. That points to 2U.
- Only a few SSDs for the OS and VMs? Ten 2.5-inch bays (R660, or DL360 with the 2 SFF option) are often enough, and 1U saves rack space.
- Expect to add drives later? Leave empty bays and a spare controller port in the plan. Changing chassis later means a migration, not an upgrade.
Step 2 — Decide by PCIe cards and GPUs
- Count cards: NICs beyond the OCP slot, external SAS HBAs, fibre channel cards, accelerators.
- Three PCIe slots is the documented ceiling on both 1U models, and on the DL360 the third slot needs the second processor.
- Any double-wide GPU means 2U on these families: the R760 lists double-wide 350 W GPUs, the R660 only single-wide 75 W cards.
Step 3 — Check cooling, noise and the room
Both Dell guides describe these servers as appropriate for an attended data center environment, so neither belongs in an open office. Both list N+1 fan redundancy. HPE's DL360 guide warns that if a single-rotor fan fails, redundancy is lost, and if two single-rotor fans or one dual-rotor fan fail, the server shuts down. HPE also requires blanking panels in empty rack spaces and a cover or card in every PCIe slot to keep airflow correct.
Note: adding a GPU or high-power processors changes thermal and power needs on both brands. Use the vendor power tools (Dell EIPT at dell.com/calc, HPE Power Advisor) on the exact configuration before you order.
Step 4 — Rack space versus growth
A 1U server halves the rack height of its 2U sibling (42.8 mm vs 86.8 mm on Dell, 4.29 cm vs 8.75 cm on HPE). That matters in a shared or colocation rack where every U is paid for. If space is not tight, the 2U model usually gives more headroom for drives, cards and GPUs for the same processors and memory.
Frequently asked questions
Does a 2U server hold more memory than a 1U server?
Not on the Dell pair in this guide: the R660 and R760 technical guides both list 32 DDR5 DIMM slots.
Can a 1U server take 3.5-inch drives?
It depends on the model. The HPE DL360 Gen11 user guide shows a 4 LFF front layout; the Dell R660 technical guide lists only 2.5-inch and EDSFF front options.
Checklist
- Three-year list of drives, PCIe cards, GPUs and memory written down.
- Drive type decided (3.5-inch, 2.5-inch or EDSFF) and bay count checked against the model's guide.
- PCIe slot count confirmed for the chosen riser and number of processors.
- Power and cooling checked with Dell EIPT or HPE Power Advisor.
- Rack units, rails and blanking panels planned.
- Read the PowerEdge buying guide for Saudi Arabia for the wider purchase decision.
Skyline can supply, configure and maintain Dell, HPE and Huawei servers under an annual maintenance contract (AMC). Contact us.
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