The refurbished Dell PowerEdge T640 16-Bay 2.5" is the SFF density configuration of Dell's 14th gen flagship tower: sixteen 2.5" hot-swap bays on the same dual-socket Cascade Lake platform as the 8-Bay 3.5" build, with the option to configure up to eight of those bays as NVMe. This is the variant we reach for when a deployment needs flagship tower compute paired with SFF storage density, IOPS-leaning workloads such as transactional databases, dense VM hosting, and VDI, or NVMe storage in a tower form factor.

We deploy this most often as serious branch-office virtualization hosts running 50-plus VMs with SFF storage tiers, tower-deployed transactional database servers (SQL, Oracle, PostgreSQL with multi-TB working sets), modest VDI deployments (40 to 80 desktops with NVMe boot tiers), tower hyperconverged nodes running Storage Spaces Direct or modest Ceph clusters, and persistent-memory-aware workloads that combine NVDIMM-N with NVMe storage tiers. The platform underneath is the full 14th gen flagship: 24 symmetric DIMM slots, a 3 TB memory ceiling, eight PCIe Gen3 slots, iDRAC9, and NVDIMM-N persistent memory.

To configure a build, call 1-800-778-1545 or use the quote form on this page and we will respond within 24 hours. Every refurbished T640 ships after a 12+ hour burn-in covering every memory channel, every PCIe slot, and every drive bay, backed by our standard 180-day warranty with 1-Year, 2-Year, and 3-Year Premium options available. Volume pricing applies at 5 units and above.

When 16 SFF Bays Is the Right Choice

The choice between the two T640 chassis is a storage-profile and GPU-envelope decision, not a tier decision: both carry the identical flagship platform. The 16-Bay 2.5" is the right pick when IOPS, drive count, or NVMe support matter more than raw capacity per dollar. Against the Dell PowerEdge T640 8-Bay 3.5" tower, this variant trades bulk LFF capacity for sixteen SFF bays and one capability the 8-Bay does not have at all: optional NVMe.

That NVMe option carries a platform tradeoff worth stating up front. On the T640, NVMe configurations cap GPU support at two cards; SAS/SATA-only configurations keep the full four-GPU envelope, because the PCIe lane budget forces the choice. So the decision between the two T640 chassis comes down to what the workload values more: bulk LFF capacity with the full four-GPU envelope (the 8-Bay 3.5"), or SFF density with optional NVMe at a two-GPU ceiling (this 16-Bay 2.5"). Everything else (processors, memory topology, memory speed, RAID family, management, boot, power range, form factor) is identical between the two.

Storage: 16 SFF Bays with Optional NVMe

The 16-Bay 2.5" chassis provides sixteen front-accessible hot-swap 2.5" bays for SAS, SATA, or optional NVMe drives. The IOPS envelope is meaningfully higher than the 8-Bay LFF build: more spindles, lower seek times on 10K SAS, and the option to step up to all-SSD or NVMe where the workload demands it. Representative capacities: sixteen 3.84 TB SAS SSDs give 61 TB raw (about 40 TB usable in RAID 6); sixteen 7.68 TB SAS SSDs give 122 TB raw; sixteen 2.4 TB 10K SAS drives give 38 TB raw at much higher IOPS than Nearline SAS. Four storage architectures we ship most often:

• All-SAS/SATA SSD density: sixteen 1.92 TB or 3.84 TB SAS SSDs in RAID 10 or two RAID 6 groups, 15 to 50 TB usable depending on drive size and RAID level. The most common build: clean IOPS for dense VM hosting and transactional databases, with the option of dual high-TDP CPUs and the full four-GPU envelope alongside. PERC H740P is the default controller.
• SSD cache plus HDD capacity tier: two to four SAS SSDs in RAID 1 or RAID 10 for hot data, twelve to fourteen 2.4 TB 10K SAS drives in RAID 6 for capacity, 25 to 35 TB usable. A strong balance of IOPS for hot data and capacity for bulk content.
• NVMe plus SAS hybrid (up to 8 NVMe): eight NVMe drives (1.6 TB, 3.2 TB, or 6.4 TB Dell-qualified SSDs) in dedicated front bays plus eight SAS/SATA drives. NVMe bypasses the PERC and connects directly to CPU PCIe lanes for low-latency IOPS. The build we ship for heavy OLTP SQL, Exchange with large mailbox stores, and VDI boot tiers. GPU support caps at two cards in this configuration.
• All-NVMe (specialist 24-Bay variant): the platform supports an all-NVMe 24-Bay 2.5" specialist chassis we do not stock as a separate SKU. If all-NVMe tower deployment is the requirement, contact us for sourcing; for datacenter all-NVMe, rack platforms are better-positioned.

For boot, the T640 uses a BOSS PCIe card (dual mirrored M.2 SATA in hardware RAID 1, cold-swap), keeping the OS off the sixteen front bays. We specify BOSS on every production build. RAID guidance differs from the 8-Bay LFF: with sixteen SAS drives, RAID 6 with two hot spares (14 in the set plus 2 spares) is a clean default; RAID 10 across 14 drives gives stronger write IOPS at half the usable capacity and is our recommendation for write-heavy SQL or Exchange. RAID 5 is acceptable on short-rebuild SSD arrays, but we default to RAID 6 for production unless the IOPS budget specifically calls for RAID 10. NVMe drives are not behind the PERC, so NVMe RAID is OS-level (Storage Spaces, ZFS, mdraid); OS choice drives the NVMe storage architecture.

Storage Controllers

The 16-Bay 2.5" supports the full 14th gen flagship PERC family in a dedicated controller slot that leaves all eight PCIe slots free:

• PERC H740P (8 GB NV cache, battery-backed): our top pick for SAS/SATA on this variant, and the right default for the IOPS-leaning workloads it targets.
• PERC H730P (2 GB NV cache, battery-backed): general-purpose for read-leaning mixes.
• PERC H330 (no cache): light workloads only.
• HBA330 (pass-through HBA): for Storage Spaces Direct, Ceph, and ZFS.
• PERC S140 (software RAID via the C620 chipset): dev and test only. We do not quote S140 for production.
• PERC H840 (external, 8 GB cache): for SAS shelf expansion.

One thing specific to this chassis: NVMe drives do not sit behind the PERC. In NVMe configurations the NVMe bays connect directly to CPU PCIe lanes, so hardware RAID across NVMe is not available on this platform (NVMe hardware RAID arrives with the 16th gen H965i lineage). Plan NVMe redundancy at the OS layer.

Processors: 14th Gen Skylake-SP and Cascade Lake-SP

Up to two Intel Xeon Scalable processors on the LGA 3647 socket, 1st gen Skylake-SP or 2nd gen Cascade Lake-SP, drop-in compatible with a BIOS update. For new deployments in 2026 we spec 2nd gen Cascade Lake for the performance per watt and the widely available Refresh SKUs (Gold 6230R, Gold 6248R, Gold 6258R). Up to 28 cores per socket (Platinum 8280) and CPUs up to 205W TDP.

For the 16-Bay 2.5" specifically, the IOPS-leaning workload mix (dense VM hosting, transactional databases) usually justifies more cores than the bulk-capacity 8-Bay build, so our default is the Gold 6248R (24 cores, 3.0 GHz, 205W) or the Platinum 8280 (28 cores, 2.7 GHz, 205W) for maximum VM density. The chassis carries the high-performance heatsinks those 205W CPUs require. Single-socket builds are supported but cut memory to 12 DIMMs and PCIe to three slots; on a flagship tower that is rarely the right call, and the T440 is better-positioned for single-socket needs.

Memory: 24 DIMMs Symmetric, Up to 3 TB

24 DDR4 DIMM slots in a fully symmetric topology (12 per CPU, six channels at two DIMMs per channel). Speed reaches 2933 MT/s at 1 DIMM per channel on Cascade Lake, dropping to 2666 MT/s at 2 DPC under full population; Skylake-SP is 2666 MT/s throughout. Maximum 3 TB with 24 x 128 GB LRDIMMs (3DS), 1.5 TB with 64 GB DIMMs. For the VM-host and database workloads this variant targets, 768 GB to 1.5 TB is the typical configuration we ship.

NVDIMM-N persistent memory is supported: up to 12 x 16 GB modules (192 GB), requiring both CPUs and following specific population rules (mixable with RDIMM, not with LRDIMM). On the 16-Bay 2.5" this pairs naturally with the NVMe storage option for transactional workloads that want both a persistent metadata tier and low-latency NVMe data. Persistent memory is unique to the T640 in Dell's tower line.

Networking and PCIe Expansion

Two onboard 10 GbE BASE-T LOM ports (Broadcom 57416) are standard, sufficient for most SMB and remote-site virtualization with iSCSI or NFS storage networking. rNDC options add dual 10 GbE SFP+, dual 25 GbE SFP28 (Mellanox ConnectX-4 Lx), or quad 1 GbE. For serious virtualization on this variant we typically add a 25 GbE Mellanox ConnectX-4 Lx PCIe card.

The chassis carries up to 8 PCIe Gen3 slots plus a dedicated PERC slot with both CPUs installed; slots 4 through 8 require the second processor, and single-CPU builds expose only 3 slots. On the 16-Bay 2.5" the PCIe lane budget is where the NVMe-versus-GPU tradeoff lives: NVMe front bays consume lanes that would otherwise feed GPU slots, which is why NVMe configurations cap GPUs at two.

GPU Support: Up to Four GPUs (Two with NVMe)

In SAS/SATA-only configurations the 16-Bay 2.5" supports the full four 300W GPU envelope, matching the 8-Bay 3.5" build and far ahead of the single-GPU T440. NVMe configurations cap GPU support at two cards, because the NVMe bays and the GPU slots compete for the same PCIe lanes. Qualified cards have included the NVIDIA Tesla V100, T4, A10, A30, A40, A100, and RTX series, plus AMD MI-series; we confirm the qualified list at quote time.

The practical guidance: if the deployment wants office-deployed multi-GPU compute and SFF storage but not NVMe, this variant delivers four GPUs and sixteen SAS/SATA bays together. If it wants both four GPUs and NVMe, the platform cannot do it; use the 8-Bay 3.5" for four GPUs plus bulk storage, or move to a rack platform. The four-GPU-plus-NVMe combination is genuinely impossible on this platform, not merely discouraged.

Management: iDRAC9 Generation

iDRAC9 is standard. We strongly recommend the iDRAC9 Enterprise license on any production T640: virtual console, virtual media, Lifecycle Controller firmware automation, OpenManage Enterprise group management, and SupportAssist diagnostics. The security baseline includes TPM 2.0, Silicon Root of Trust, Secure Boot, System Lockdown, and Quick Sync 2.0 mobile management. For the unattended branch and remote sites where flagship towers live, remote console is the feature that saves a truck roll.

Power and Cooling

Power profiles for the 16-Bay 2.5" differ slightly from the 8-Bay build. NVMe drives draw less than equivalent SAS spinning drives, but the dense VM and transactional-database workloads this variant targets usually run the CPUs harder. All PSUs are hot-plug and support redundant 1+1 operation:

The 1100W pair handles most non-GPU SFF builds; 1600W suits two-GPU NVMe builds; 2400W is required for four-GPU SAS/SATA builds. Two-GPU-or-greater builds should run on 200 to 240V AC to avoid PSU derating at low line. Cooling uses the same redundant fan envelope as the rest of the platform; four-GPU plus dual 205W CPU builds run noticeably louder than mid-range configurations.

Physical Specs & Platform Notes

• Form factor: 5U tower, rack-convertible with the optional rack conversion kit. Chassis depth roughly 726 mm. In rack mode it consumes 5U.
• PCIe expansion: up to 8 PCIe Gen3 slots plus a dedicated PERC slot with both CPUs; slots 4 through 8 require the second processor. On this variant the lane budget is shared with the NVMe backplane.
• Parts availability: excellent. Shares platform, PERC family, BOSS module, iDRAC9, and PSUs with the high-volume R740 and R740xd, so spares are mature and widely stocked. Dell ProSupport on 14th gen is near end of extended support, so third-party maintenance is the standard production support path in 2026.
• Accessories we recommend: the BOSS-S1 boot card; the rack conversion kit if rack deployment is planned (sold separately); the iDRAC9 Enterprise license; and a 25 GbE Mellanox ConnectX-4 Lx NIC for dense virtualization.
• Platform notes: the 16-Bay 2.5" backplane and drive cage are not field-convertible to the 8-Bay 3.5" LFF layout, so choose the storage profile at purchase; NVMe and four-GPU are mutually exclusive; NVMe sits outside the PERC (OS-level RAID only); BOSS is cold-swap.

Our Assessment

Where it excels: the T640 16-Bay 2.5" is the right call when a deployment needs flagship-tier tower compute paired with SFF drive density, IOPS-leaning storage, or NVMe support. It is strong for serious branch-office virtualization (50-plus VMs with SFF tiers), tower-deployed transactional databases (SQL, Oracle, PostgreSQL with multi-TB working sets), modest VDI with NVMe boot tiers (40 to 80 desktops), tower hyperconverged nodes (Storage Spaces Direct, modest Ceph), and NVDIMM-N plus NVMe persistent-memory hybrid architectures. Optional NVMe is its clearest differentiator over the bulk-capacity 8-Bay build.

Where to look instead: if bulk LFF capacity per dollar is the priority, the T640 8-Bay 3.5" delivers more terabytes at lower IOPS. If a build needs four GPUs and NVMe at once, the platform forces a choice and a rack platform is the better answer. If the workload fits the smaller T440 envelope, the T440 16-Bay 2.5" is cheaper and right-sized. If rack form factor is acceptable, the R740xd is better-positioned for SFF density. These are linked in the sections above and below.

Bottom line: this is the 14th gen flagship tower to buy when you need SFF storage density, optionally NVMe, serious dual-socket compute, and a tower form factor. If four GPUs matter more than NVMe, the 8-Bay 3.5" is the better build on the same platform. If SMB or remote-office budget is the constraint, the T440 16-Bay is the cheaper-and-sufficient alternative. If you have rack space, the R740xd is the stronger choice. We will make that call with you at quote time.

Honest Limitations

• NVMe and four GPUs cannot coexist. Per Dell's platform spec, NVMe configurations cap GPUs at two. The PCIe lane budget cannot feed both eight NVMe drives and four full-bandwidth GPU slots. If both matter, the platform is wrong; consider rack alternatives.
• NVMe on PCIe Gen3 is bandwidth-limited. Roughly 3.5 GB/s per Gen3 x4 NVMe drive, well below Gen4 (about 7 GB/s) and Gen5 (about 14 GB/s). For workloads that saturate NVMe sequential throughput, a 16th gen R660 or R760 with Gen5 NVMe is the better platform.
• NVMe bypasses the PERC. No hardware RAID across NVMe on this platform; NVMe redundancy is OS-level (Storage Spaces, ZFS, mdraid). Choose the OS accordingly.
• Storage profile is fixed at purchase. The 16-Bay 2.5" backplane and cage are not field-convertible to the 8-Bay 3.5" LFF layout. Pick the storage profile correctly up front.
• PCIe Gen3 ceiling. No Gen4 or Gen5 expansion. Gen4 NICs and HBAs run at about half bandwidth; H100 and Gen5 GPUs are throttled. Match cards to a Gen3-saturating profile.
• Single-socket loses half the platform. Single-CPU builds expose only 12 DIMMs and 3 PCIe slots; the T440 is better-positioned for single-socket needs.
• 5U footprint is large. Rack-converted it consumes 5U against the R740xd's 2U. The R740xd 24-Bay 2.5" gives 50 percent more SFF bays in 2U; the tower wins only when tower form factor is required.
• Maximum build is power-intensive. Dual Platinum 8280, 1.5 TB RAM, sixteen SAS SSDs, and four 300W GPUs draws roughly 2050W and requires dual 2400W PSUs on 200 to 240V AC. Verify circuit capacity at quote time.
• iDRAC9 Express is insufficient for production. Always add Enterprise, especially at unattended sites.
• No direct flagship-tower successor in 15th or 16th gen. The T550 and T560 are smaller-platform (16 DIMMs, no NVDIMM-N). For 24-DIMM, 3 TB, or NVDIMM-N tower needs, the 14th gen T640 remains the answer in 2026, with the usual caveats of buying refurbished 14th gen.

Workload Fit

Where to Look Instead

If the 16-Bay 2.5" is not the right fit, these are the configurations we point customers to:

• Dell PowerEdge T640 8-Bay 3.5" tower: the same flagship platform with eight LFF bays for bulk capacity and the full four-GPU envelope. The pick when capacity per dollar and four GPUs matter more than SFF density or NVMe.
• Dell PowerEdge T440 8-Bay 3.5" tower and Dell PowerEdge T340 8-Bay 3.5" entry tower: the 14th gen mid-tier and entry towers for SMB and remote-office deployments that fit a smaller envelope.
• Dell PowerEdge R740xd 12-Bay 3.5" rack server: the same 14th gen platform in 2U with greater storage density and broader NVMe options, the better fit whenever rack space is available.
• Dell PowerEdge T630 8-Bay 3.5" (13th gen flagship tower) for a budget step-down, the Dell PowerEdge T560 12-Bay 3.5" (16th gen tower) for the current DDR5 generation, or the Dell PowerEdge R650 8-Bay 2.5" (15th gen rack) for a newer rack platform.

Ready to Configure?

Tell us your workload, target memory capacity, drive count and capacity per drive (and whether SAS SSD, 10K SAS, or NVMe is the priority), single-socket or dual-socket, whether GPU acceleration is needed and how many cards, and whether NVDIMM-N persistent memory is in scope. We will turn that into a specific build and a firm quote.

Call 1-800-778-1545 or submit the quote form on this page and we will respond within 24 hours. Every T640 we ship is tested with a 12+ hour burn-in and backed by a 180-day warranty, with extended 1-Year, 2-Year, and 3-Year Premium coverage available. Volume pricing applies at 5 units and above.