The R640 and R740 are Dell's mainstream 14th generation rack servers. The R640 is 1U, the R740 is 2U, and the usual assumption is that the larger chassis is the more capable one. On storage interface that assumption is wrong: the 1U R640 is the platform with NVMe backplanes, and the R740 as listed is not.
Drive configurations compared
These are the chassis configurations TekBoost lists for each platform.
| PowerEdge R640 | PowerEdge R740 | |
|---|---|---|
| Form factor | 1U rackmount | 2U rackmount |
| Generation | Dell 14th generation | Dell 14th generation |
| 2.5" configurations | Up to 8 SAS/SATA Up to 10 SAS/SATA |
Up to 8 SAS/SATA Up to 16 SAS/SATA |
| 3.5" configurations | Not listed | Up to 8 SAS/SATA |
| NVMe-capable backplanes | Up to 4 NVMe/SAS/SATA + 6 SAS/SATA Up to 8 NVMe/SAS/SATA + 2 SAS/SATA Up to 10 NVMe/SAS/SATA |
Not listed |
| Maximum listed drive count | 10 | 16 |
| Storage controllers | PERC S140 software RAID (SATA only), PERC H330, PERC H730P 2GB, PERC H740P 8GB | |
What the difference actually means
NVMe is the surprise, and it runs the other way
Three NVMe-capable backplanes are listed for the 1U R640 — a 4+6 split, an 8+2 split, and an all-10 configuration — and none is listed for the R740. If the design calls for NVMe in hot-plug front bays, the smaller chassis is the one that supports it.
Being precise about the splits: on the 4+6 and 8+2 configurations only part of the bay count takes NVMe, and a backplane being NVMe-capable is not the same as a unit arriving with NVMe drives fitted.
Capacity runs the expected way
The R740 reaches 16 x 2.5" against the R640's 10, and adds an 8 x 3.5" option the R640 does not have at all. For bulk capacity on spinning disks, the 2U chassis is the only one of the two in the conversation.
Rack units are the other half of the trade
Two R640s occupy the same height as one R740 and give two independent machines with two sets of power supplies and fans. Where capacity per rack unit matters and storage lives on a SAN or NAS, that is frequently the better shape — and it is the reason 1U servers remain the default in dense environments.
Both share the same controller range
PERC S140 software RAID, H330, H730P and H740P are listed for both. Two things follow. S140 is SATA only, so any plan involving SAS drives needs a hardware controller on either platform. And the controller, not the chassis, is usually what limits a large array — so specify it deliberately rather than accepting whatever the unit shipped with.
Choosing between them
- NVMe in front bays — the R640, because the R740 does not list it.
- More than ten drives, or 3.5" drives — the R740.
- Density, or scaling by adding nodes — the R640.
- Expansion headroom for larger cards — the R740, where 2U gives physical room a 1U chassis cannot.
What these figures describe
The table sets out the chassis configurations these platforms were built in, not the backplane fitted to a particular unit. Drive configuration is decided at build and cannot be changed by adding caddies afterwards.
Where to go next
- Dell PowerEdge R640 specifications and options
- Dell PowerEdge R740 specifications and options
- R440 compared with R640
- R740 compared with R740XD
- Which Dell PowerEdge rack server?
- Plan drive capacity and RAID with the Storage & RAID Advisor
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. To have a configuration checked against real stock, request a quote.