R640 vs R650

The R640 and R650 are both 1U, 2-socket Dell PowerEdge rack servers built for the same dense scale-out role. The R650 moves to a 3rd Generation Xeon Scalable platform with PCIe Gen4, more cores per socket, and a higher memory ceiling; the R640 is the proven 14th generation platform it replaced. If your workload needs PCIe Gen4 bandwidth, more than 28 cores per socket, or a larger persistent-memory allowance, the R650 is the current platform. If it doesn't, the R640 does the same job for less, with wider refurbished availability.

Quick comparison

Key differences

Both are 1U, 2-socket servers built around the same dense scale-out chassis philosophy. The practical differences below all follow from the generation gap: 3rd Generation Xeon Scalable versus 1st/2nd, PCIe Gen4 versus Gen3, and a move from rNDC to OCP 3.0 networking on the R650.

CPU & compute

The R640 supports up to two 1st or 2nd Generation Intel Xeon Scalable processors, up to 28 cores per socket. The R650 supports up to two 3rd Generation Intel Xeon Scalable processors, up to 40 cores per socket, with a faster Intel UPI interconnect between sockets. For core-dense workloads, the R650's higher per-socket core ceiling is the most direct capacity difference.

Memory

The R640 has 24 DDR4 DIMM slots (12 per CPU), supporting RDIMM, LRDIMM, NVDIMM, and Intel Optane DC Persistent Memory (Apache Pass) up to 2933 MT/s, with a 7.68 TB ceiling using DCPMM and LRDIMM together. The R650 has 32 DDR4 DIMM slots (16 per CPU), supporting RDIMM, LRDIMM, and 3DS DIMM up to 3200 MT/s, with a larger persistent-memory allowance — up to 16 Intel Optane Persistent Memory 200 Series modules against the R640's 12. Both platforms require registered ECC DDR4 DIMMs; neither supports unbuffered memory.

Storage & NVMe

The R640's front-bay options top out at 10x2.5" (up to 8 NVMe-capable) or 4x3.5". The R650 offers 4x3.5", 8x2.5", or 10x2.5" front-bay configurations, with SAS, SATA, and NVMe supported across those options per Dell's own published comparison. Drive type support (12Gb SAS, 6Gb SATA, NVMe) is listed as identical between the two platforms by Dell; the difference is in chassis flexibility and PCIe SSD attachment, where the R650 adds a rear direct-attach option (up to 10 front plus 2 rear) that the R640 does not have.

PCIe / expansion

The R650 moves to PCIe Gen4, while the R640 uses PCIe Gen3. Both support up to 3 PCIe slots, with the R650's 3rd Generation Xeon platform providing 64 PCIe Gen4 lanes per CPU against the R640's 48 PCIe Gen3 lanes per CPU. Both platforms support up to three single-width GPUs (NVIDIA T4-class), with Dell's own comparison listing a small wattage increase on the R650 (75W per card versus the R640's 70W). For most accelerator use cases, the generational PCIe bandwidth difference matters more than this small wattage gap.

Virtualization

Both are proven 1U virtualization hosts. Dell's R650 Technical Guide specifically lists high-density virtualization and cloud-native applications among the platform's primary target workloads, supported by the higher core density per socket. For a given core and memory budget, the R650's higher core count generally means fewer physical hosts for the same number of virtual machines, though the actual gain depends on the specific hypervisor and workload.

Database & enterprise applications

Dell's R650 Technical Guide lists large traditional or in-memory databases with persistent memory as a primary target workload, supported by the platform's larger persistent-memory ceiling (up to 16 Intel Optane Persistent Memory 200 Series modules versus the R640's 12 Apache Pass modules). For in-memory database workloads specifically, the R650's larger PMem allowance and faster memory are the more direct upgrade path.

When the R640 makes more sense

• Your workload doesn't require PCIe Gen4 bandwidth or more than 28 cores per socket.
• You want the widest refurbished availability and the lowest cost for a proven 1U platform.
• Your drive count fits comfortably within 10x2.5" or 4x3.5" front bays.
• Your networking needs are met by rNDC options rather than OCP 3.0.

When the R650 makes more sense

• You need more cores per socket, faster memory, or a larger persistent-memory ceiling for in-memory databases.
• Your workload benefits from PCIe Gen4 bandwidth, particularly NVMe-heavy storage or Gen4 accelerator cards.
• You need OCP 3.0 networking rather than a traditional rack network daughter card.
• You're standardizing on current-generation hardware for a longer support runway.

Upgrade considerations

Drive backplane, riser configuration, and CPU socket count are chassis-level decisions made when a unit was originally built, on both platforms. A backplane cannot be changed later by adding drive caddies. Confirm the installed backplane, riser kit, and processor count on any specific unit against the applicable Dell specification sheet before assuming a configuration can be expanded after purchase. The R650 also adds a hot-plug BOSS S2 boot module, an improvement over the R640's non-hot-plug BOSS. Because the R650 is a newer platform, refurbished unit availability and configuration options are currently more limited than for the R640; confirm current stock before committing to a specific R650 configuration.

Common questions

Where to go next

• Dell PowerEdge R640 specifications and options
• Configure the Dell PowerEdge R640
• Dell PowerEdge R650 specifications and options
• Dell PowerEdge 13G vs 14G vs 15G vs 16G Guide
• Plan drive capacity and RAID with the Storage & RAID Advisor
• Browse refurbished Dell PowerEdge servers

Hardware bought from TekBoost carries our standard 3-year warranty with Next Business Day part replacement, subject to the terms, exclusions and conditions on that page. Every system is tested before shipment. The R650 currently uses a custom quote rather than online configuration, so request a quote to confirm current sourcing and pricing for either model.

Methodology and sources

Last reviewed: 2026-11-12. Specifications drawn directly from Dell's official PowerEdge R640 Technical Guide (Regulatory Model E39S Series, Rev. A08, June 2021) and the official Dell PowerEdge R650 Technical Guide (Regulatory Model E69S Series, Rev. A02, September 2021), including Dell's own published R650-vs-R640 generational comparison table. Configuration-dependent specifications — PCIe riser mix, storage bay count, GPU count, and PSU wattage — are described as ranges rather than single figures, consistent with Dell's own published riser and chassis option tables.