Dell PowerEdge R660 Dual-Socket 1U Rack Server Review

Verdict: The PowerEdge R660 is the most balanced 1U server Dell has built. It takes the full 32-slot DDR5 memory architecture and Gen5 I/O of the 2U R760 and compresses them into a single rack unit, then adds E3.S NVMe support that most 1U competitors still lack. If your data center charges by the U — or your workload is dense virtualization, CDN, or database analytics — the R660 is close to a default choice. It gives up GPU headroom and drive capacity to get there, and that trade-off is the whole story of this review.

Rating: 4.5 / 5

Pros	Full 32 DDR5 DIMM slots and 8 TB capacity in 1U; up to 16 E3.S Gen5 NVMe bays; three full-height Gen5 x16 slots; 64-core 5th Gen Xeon support; optional liquid cooling
Cons	Only 3 PCIe slots and 75 W single-width GPUs — no serious GPU acceleration; max 10 x 2.5-inch drives; 1U thermals demand careful CPU selection
Best for	High-density virtualization, VDI brokers, CDN and web tiers, database analytics, HPC compute nodes
Skip if	You need double-width GPUs, more than 10 drives, or maximum storage capacity per chassis

What the R660 Actually Is

The PowerEdge R660 is Dell’s 16th-generation 1U, two-socket rack server, replacing the R650. It runs 4th and 5th Generation Intel Xeon Scalable processors — up to 56 cores on 4th Gen and 64 cores on 5th Gen — on the Intel C741 chipset, with DDR5 memory and PCIe 5.0 throughout.

The important detail is that Dell did not shrink the memory architecture to fit 1U. The R660 keeps the same 32 DDR5 DIMM slots as the 2U R760, which is unusual in this form factor. That single decision is what makes the platform interesting: most 1U servers force you into 16 DIMMs and half the memory ceiling.

PowerEdge R660 Specifications

Item	Specification
Form factor	1U rack server
Processors	1-2 x 4th Gen Intel Xeon Scalable (up to 56 cores) or 5th Gen Intel Xeon Scalable (up to 64 cores); optional Intel QuickAssist Technology
Chipset	Intel C741
Memory	32 x DDR5 RDIMM slots, up to 8 TB; up to 4800 MT/s (4th Gen) or 5600 MT/s (5th Gen)
Drive bays	8 or 10 x 2.5-inch SAS/SATA/NVMe (max 153.6 TB); 14 or 16 x EDSFF E3.S Gen5 NVMe (max 204.8 TB); rear 2 x 2.5-inch or 2 x E3.S
Boot device	BOSS-N1 (hardware RAID 2 x M.2 NVMe)
Storage controllers	PERC H965i, H755, H755N, H355, HBA355i (internal); HBA355e, PERC H965e (external); software RAID S160
PCIe expansion	Up to 3 slots: Gen5 x16 full-height, 3/4-length, plus low-profile options
GPU support	Up to 3 x 75 W single-width accelerators
Network	Optional 2 x 1GbE LOM and/or OCP 3.0
Power supplies	Hot-swap redundant: 700 W / 800 W / 1100 W / 1400 W / 1800 W (Titanium and Platinum, AC and DC)
Cooling	Smart Flow air cooling; optional Direct Liquid Cooling (requires rack manifold and CDU)
Management	iDRAC9, iDRAC Direct, Redfish API, OpenManage Enterprise, CloudIQ, Quick Sync 2
Security	Silicon Root of Trust, signed firmware, Secure Boot, Secure Erase, System Lockdown, TPM 2.0 (FIPS/CC-TCG), Secured Component Verification, SED encryption
Operating systems	Windows Server with Hyper-V, Red Hat Enterprise Linux, SUSE Linux Enterprise Server, Ubuntu Server LTS, VMware ESXi

Performance and Architecture: What the Numbers Mean

At the platform level, the R660’s value comes from three ratios rather than raw peak numbers.

Cores per U. Two 64-core 5th Gen Xeon processors put 128 cores in a single rack unit. For virtualization hosts, that is the highest core density Dell offers outside the AMD R6615/R6625 line — and it comes with the per-core performance Intel is known for, which matters for licensing models priced per core and for latency-sensitive databases.

Memory per U. 8 TB across 32 DIMMs in 1U is the headline. Eight channels per socket at up to 5600 MT/s give the bandwidth to feed those cores, and the 32-slot layout means you can populate for capacity without dropping to a single DIMM per channel and losing bandwidth.

Storage per U. The E3.S option is what separates the R660 from its predecessor. Sixteen E3.S Gen5 NVMe drives deliver up to 204.8 TB of all-flash capacity in 1U, with direct CPU-attached lanes and no PCIe switch contention. That is enough to build a genuinely storage-dense 1U node for SDS or analytics — something the R650 could not do.

Where It Excels

Dense virtualization and VDI. 128 cores and 8 TB of memory per U makes the R660 a consolidation machine. A handful of R660s can absorb a rack of older two-socket servers, with the memory ceiling to keep overcommit ratios sane.

Database and analytics tiers. High clock speeds on 5th Gen Xeon, 32 DDR5 slots and Gen5 NVMe front-end storage make this a credible 1U database node — the form factor no longer forces a 2U compromise.

Web, CDN and edge tiers. Low power per core, redundant everything, and a shallow 1U footprint suit horizontally scaled front-end fleets where rack units and watts are the real cost drivers.

HPC and compute-only nodes. Three full-height Gen5 x16 slots accept 200 GbE or InfiniBand adapters, which is exactly what a compute node in a modern cluster needs.

Where It Falls Short

GPU acceleration is essentially off the table. Three 75 W single-width cards will run inference at the edge or transcode video, but this is not a platform for training or for L40S-class work. If GPU density matters, the 2U R760 or a GPU-dedicated chassis is the correct answer.

Drive capacity is capped at 10 x 2.5-inch (or 16 E3.S). For capacity-tier storage, SDS with 3.5-inch drives, or backup targets, the R660 is the wrong tool — the R760’s 12 x 3.5-inch layout exists for that reason.

1U thermal reality. High-TDP processors in 1U need the right heatsink and fan profile, and sustained all-core workloads will run closer to thermal limits than in 2U. Dell offers Direct Liquid Cooling for the hottest configurations, but DLC is a rack-level commitment, not a checkbox.

Only three PCIe slots. Adequate for a NIC plus an HBA plus one spare, but tight if you need multiple fabrics or a RAID controller alongside high-speed networking.

R660 vs R650 vs R760

Feature	R650 (previous gen)	R660 (this review)	R760 (2U)
Form factor	1U	1U	2U
Processors	3rd Gen Xeon, up to 40 cores	4th/5th Gen Xeon, up to 64 cores	4th/5th Gen Xeon, up to 64 cores
Memory	32 DDR4, up to 8 TB	32 DDR5, up to 8 TB, 5600 MT/s	32 DDR5, up to 8 TB
PCIe	Gen4	Gen5, 3 slots	Gen5, up to 8 slots
Max drives	10 x 2.5-inch	10 x 2.5-inch or 16 x E3.S	24 x 2.5-inch or 12 x 3.5-inch
GPU	2 x 75 W SW	3 x 75 W SW	2 x 350 W DW / 6 x 75 W SW

The R650-to-R660 jump is a full platform generation: DDR5, Gen5, E3.S and 60% more cores per socket. The R660-to-R760 decision is purely about density versus expandability — one rack unit and lower cost per node, against GPU headroom, drive capacity and more slots.

Who Should Buy It

Buy the R660 if your constraints are rack units, core density and memory ceiling, and your workloads are CPU-and-memory-bound rather than GPU-bound. Skip it if you need acceleration, deep storage, or the widest possible expansion — those requirements point at 2U.

For most enterprise refreshes, the sensible pattern is a mixed fleet: R660 for compute-dense virtualization and web tiers, R760 for storage and GPU nodes. That combination usually beats standardizing on one model.

Frequently Asked Questions

Is the Dell PowerEdge R660 a good server? Yes. It is one of the few 1U servers that keeps 32 DDR5 DIMM slots and 8 TB of memory capacity while adding Gen5 E3.S NVMe. Its limitations — three PCIe slots and 75 W GPUs — are form-factor constraints, not design flaws.

How many cores does the R660 support? Up to two 5th Generation Intel Xeon Scalable processors with 64 cores each, for 128 cores and 256 threads per 1U server. 4th Gen configurations top out at 56 cores per socket.

What is the maximum storage in an R660? Up to 10 x 2.5-inch SAS/SATA/NVMe drives (153.6 TB), or 16 x EDSFF E3.S Gen5 NVMe drives (204.8 TB), plus two rear drives.

Can the R660 run GPUs? Only single-width cards up to 75 W each, three maximum. It is suitable for light inference and transcoding, not for AI training or high-power accelerators.

R660 or R760 — which should I buy? Choose the R660 for maximum compute and memory density per rack unit. Choose the R760 when you need double-width GPUs, 3.5-inch drives, or more than three PCIe slots.