Dell PowerEdge R740xd: Capacity Without the Compromise

The PowerEdge R740xd is Dell's 14th-generation 2U storage platform and the direct successor to the R730xd. The headline is the bay count — up to 32 × 2.5-inch drives or 18 × 3.5-inch drives in a single 2U chassis — but the change that matters more day to day is the socket. Moving to LGA 3647 and Xeon Scalable takes memory from four channels per socket to six, which is why the same twenty-four DIMM slots behave very differently here than on the previous generation.

What changed under the lid

The R740xd takes first-generation (Skylake-SP) and second-generation (Cascade Lake) Xeon Scalable processors, up to 28 cores and 205 W per socket — 56 cores and 112 threads in one node. Both generations bring AVX-512, with one or two FMA units depending on the SKU tier, and Cascade Lake adds VNNI instructions for INT8 inference. As with any generational jump, the two processor families cannot be mixed in one server, and second-generation parts require a BIOS new enough to know them.

Memory is the real story. Twelve slots per socket is six channels, two DIMMs deep. The Cascade Lake SKUs rated for it run DDR4 at 2933 MT/s with one DIMM per channel and step back to 2666 MT/s at two per channel; Silver and Bronze parts are rated lower, at 2400 and 2133 MT/s, so check the processor before assuming the platform maximum. Six channels at 2933 MT/s is roughly 140.8 GB/s of theoretical bandwidth per socket, against about 76.8 GB/s from four channels at 2400 MT/s on the older platform. The population rule follows from that: fill all six channels on each socket before adding a second DIMM to any of them. Six 32 GB modules per socket gives 384 GB per node at full speed. The chassis reaches 3 TB with 24 × 128 GB LRDIMMs, but only with the high-memory processor SKUs — the M-suffix parts on first generation, L-suffix on second — because standard Xeon Scalable parts cap at 768 GB per socket, or 1.5 TB per node. Second-generation processors also support Optane persistent memory alongside DRAM, under specific population rules.

Bays: front, middle, and back

The xd chassis holds drives in three places. The front backplane takes 24 × 2.5-inch or 12 × 3.5-inch. A mid-plane between the fan wall and the risers adds four more in either format. The rear takes four 2.5-inch or two 3.5-inch. That is up to 32 small-form-factor or 18 large-form-factor drives without an external enclosure.

Two caveats. The mid-plane sits in the middle of the airflow path, so Dell gates it behind particular cooling configurations — check the configuration rules before pairing it with the highest-TDP processors. And a fully loaded chassis is heavy enough that you should plan the rails and the lift before it arrives.

The other significant addition is BOSS-S1: two M.2 SATA devices mirrored on a small card, dedicated to booting. It removes the old dilemma of sacrificing data bays or trusting an SD module for the hypervisor. On a storage node, that is worth more than it sounds.

Flash, controllers, and slots

The R740xd's NVMe story is what separates it from the previous generation. With the all-NVMe front backplane and PCIe extender risers, the chassis supports up to 24 direct-attached NVMe drives; mixed backplanes with a smaller NVMe tier in front of SAS capacity are the more common build. Controller options run from the HBA330 host bus adapter for software-defined storage through the PERC H730P with 2 GB of cache and the H740P with 8 GB of non-volatile cache for hardware RAID, plus the H840 for external enclosures. The same rule as always applies: Ceph, ZFS, Storage Spaces, and vSAN want the HBA, not a RAID controller in pass-through mode.

Slot count reaches eight PCIe 3.0 slots with both sockets populated, riser configuration permitting. Note the generation carefully — 14G is PCIe 3.0 only. PCIe 4.0 arrived on Dell's next platform generation, so if the design calls for Gen4 NVMe or 200 GbE, this is not the chassis. Count the lanes as well as the slots: a PCIe 3.0 x16 slot carries roughly 126 Gb/s of usable bandwidth, which covers 25 GbE and a single 100 GbE port comfortably but leaves a dual-port 100 GbE adapter unable to drive both ports at line rate. For SAS, SATA, and NVMe mixes it has lanes to spare. Management is iDRAC9, with virtual console and virtual media requiring the Enterprise license tier. Power supplies are hot-plug and redundant, from 495 W up to 2400 W depending on how the machine is configured, with the largest units requiring a high-line 200–240 V feed.

R730xd versus R740xd

	R730xd	R740xd
Processors	Xeon E5-2600 v3 / v4	Xeon Scalable 1st / 2nd gen
Socket	LGA 2011-3	LGA 3647
Max cores per socket	22	28
Memory channels per socket	4	6
DIMM slots	24	24
Peak memory speed	2400 MT/s	2933 MT/s at 1 DIMM per channel
Max 2.5 in bays	26 (24 front + 2 rear)	32 (24 front + 4 mid + 4 rear)
Max 3.5 in bays	16 (12 front + 4 mid)	18 (12 front + 4 mid + 2 rear)
NVMe bays	Up to 4	Up to 24
PCIe slots (2 CPUs)	Up to 6, Gen3	Up to 8, Gen3
Dedicated boot device	Internal dual SD module	BOSS-S1, two M.2 in RAID 1
Management	iDRAC8	iDRAC9
Vector extensions	AVX2	AVX-512 (VNNI on 2nd gen)

Where it fits

The R740xd suits three situations particularly well. Consolidation is the first: 28-core processors mean one node can absorb what two older nodes were doing, which matters when the hypervisor bills a minimum of sixteen cores per populated socket regardless of what is installed. Hybrid storage is the second — an NVMe tier in the front bays, capacity disks in the mid and rear bays, and the boot volume off the data path entirely. Bandwidth-sensitive work is the third, where six memory channels per socket does more for throughput than another few hundred megahertz ever would.

The honest limits: no PCIe 4.0, no CXL, and a per-socket TDP ceiling that means the highest-core-count parts need the right heatsink and cooling configuration. None of that is a problem for storage and general virtualization duty. It is a problem for GPU-dense inference builds, which belong on a different chassis.

Where to go from here

Browse the current Dell PowerEdge R740xd systems to see which backplanes, controllers, and processor pairs are available, or compare against the R730xd if the workload is disk-bound and per-core performance is not the constraint. When the specifics matter — NVMe bay count, DIMM population, HBA versus PERC, BOSS boot — assemble the exact configuration on the build your server page and send it in for a quote, and note the operating system or storage platform you plan to run so the controller choice can be checked against it.