The Dell PowerEdge R660 has no 3.5-inch drive bays. The cost-optimized R660xs has four. In Dell's 16th-generation 1U line, the cheaper machine is the only one that takes large-form-factor drives at all — and if your capacity plan is built on nearline SAS, that single fact decides which model you buy.

It is worth pausing on how unusual that is. Across the rest of its specification the R660xs behaves the way a cost-optimized variant is supposed to: half the memory slots, a lower core ceiling, a 100 W lower processor envelope. Storage is where it inverts. And nobody writes it down — not the reseller comparison pages, not the reviews.

This guide is for IT buyers and infrastructure engineers who have narrowed to the R660 server family. It covers the drive-bay split between the two models, what a single rack unit actually costs you in PCIe slots, GPU wattage and processor headroom, how Dell itself sells each machine, and what to check before you pay for a used one. Every specification below is cited to a Dell document.

Who the Dell PowerEdge R660 is for — and who should look elsewhere

The R660 is Dell's 16th-generation mainstream 1U platform: a two-socket rack server built around 4th- and 5th-Generation Intel Xeon Scalable processors, Intel Xeon Max processors and DDR5 memory. It suits virtualization hosts, front-end and middleware tiers, and any build where rack density matters more than expansion — you can rack forty-two R660 servers in a 42U cabinet.

Four buyers should look elsewhere, and it is cheaper to find that out now.

• If you need 3.5-inch drives, the R660 cannot take them at any capacity. The Dell PowerEdge R660xs can, and the next section is about exactly that.
• If you need expansion more than density — more PCIe slots, double-width accelerators, more than ten front bays — the 2U machine in the same generation fits better. Our Dell PowerEdge R760 buying guide covers that side, and carries the 16th-generation refurbished-versus-new argument in full; this guide does not repeat it.
• If your budget reaches only 15th-generation hardware, you are shopping a DDR4 platform. The Dell PowerEdge R650 is the direct predecessor — and, relevantly here, it did have a 4 × 3.5-inch chassis.
• If you are shopping the 17th generation, Dell sells the R670 alongside the R660, and Dell's R670 Technical Guide specifies up to 20 front E3.S bays against the R660's 16. The generational argument is in the R760 guide.

If you have not yet narrowed to a model at all, start with our guide to how to choose a Dell PowerEdge model and generation, which covers what the suffixes mean across the range. This article assumes the R660 family is already on your shortlist.

The Dell PowerEdge R660 has no 3.5-inch drive bays — the R660xs has four

Dell's 76-page PowerEdge R660 Technical Guide mentions "3.5-inch" exactly once, and it is in the column describing the previous-generation R650. The R660's own drive-bay row lists 8 × 2.5-inch, 10 × 2.5-inch, and 14 or 16 × EDSFF E3.S. There is no large-form-factor option to configure.

The two specification sheets say it in one line each. Dell's R660 sheet: "Storage options include up to 8 x 2.5" NVMe/SAS4/SATA, plus up to 10 x 2.5" NVMe/SAS4/SATA, 14/16 x NVME E3.S Gen5." The R660xs sheet leads with the opposite: "Storage options include up to 4x 3.5" HDDs/SSDs; or up to 10x 2.5" HDDs/SSDs/NVMe."

Front drive bay options across the Dell PowerEdge R660 and R660xs, from Dell's Technical Guides (E83S and E87S Rev. A04)

Platform	Front bay option	Dell's stated maximum
R660	8 × 2.5-inch NVMe	122.88 TB
R660	10 × 2.5-inch SAS/SATA/NVMe	153.6 TB
R660	14 × EDSFF E3.S Gen5 NVMe	179.2 TB
R660	16 × EDSFF E3.S Gen5 NVMe	204.8 TB
R660	3.5-inch	No option, in any configuration
R660xs	4 × 3.5-inch SAS/SATA HDD or SSD	96 TB
R660xs	8 × 2.5-inch SAS/SATA/NVMe	122.88 TB
R660xs	10 × 2.5-inch SAS/SATA/NVMe	153.6 TB
R660xs	EDSFF E3.S	No option, in any configuration

Rear bays are separate on both machines: the R660 takes up to two 2.5-inch SAS4/SATA drives (30.72 TB) or two E3.S Gen5 (25.6 TB), the R660xs up to two 2.5-inch SAS/SATA/NVMe (15.2 TB). Sources: Dell PowerEdge R660 Technical Guide (Regulatory Model E83S) and PowerEdge R660xs Technical Guide (Regulatory Model E87S, revision A04), Table 2 in each — and the 84-page R660xs guide contains no E3.S or EDSFF reference at all. Chassis and backplane detail for the xs is in Dell's R660xs installation manual.

So the two machines are not ranked, they are pointed at different problems. If you need EDSFF density in one rack unit, the R660 is the only answer in this family. If you need nearline capacity on 3.5-inch spinning disk in one rack unit, the R660xs is.

What you give up to get those four 3.5-inch bays

The R660xs halves your memory slots, cuts the processor power envelope by 100 W and drops E3.S entirely, and Dell lists no GPU option for it at all. Dell gives it 16 DDR5 slots to the R660's 32, at one DIMM per channel rather than two, with an RDIMM ceiling of 1.5 TB against 8 TB. Maximum processor TDP is 250 W against 350 W, and each socket gets up to three UPI links rather than four.

Two details are worth stating because they are commonly got wrong in both directions. PCIe is not one of the reductions — Dell specifies both machines at up to two Gen5 slots or up to three Gen4 slots. And on the Dell R660xs, the newer processors top out at fewer cores than the older ones: Dell lists up to 32 cores per socket with 4th-Generation Intel Xeon Scalable parts and up to 28 with 5th-Generation, because the higher-core-count 5th-Generation parts exceed the 250 W envelope. On the R660 the relationship runs the normal way round, 56 cores to 64.

How much memory the Dell PowerEdge R660xs actually supports

1.5 TB — with both processors installed, all sixteen slots filled, and 96 GB RDIMMs in every one of them. Dell's R660xs Technical Guide (revision A04) states "16 DDR5 DIMM slots … Supports RDIMM 1.5 TB max," and the conditions attached to that number are in the same document rather than in a footnote somewhere else.

The largest RDIMM in Dell's supported list for this platform is 96 GB, and Dell supports 96 GB modules only at 1, 6 or 8 DIMMs per processor — so the ceiling is eight modules on each of two processors, with matching populations on both. There is no second slot per channel to fill: the R660xs is a one-DIMM-per-channel design with eight slots per processor. Dell also states that memory mixing across different DIMM capacities is not supported, and that a system populated outside the supported configurations "might not boot, stop responding during memory configuration, or operate with reduced memory." Unlike its documentation for the 2U R760xs, Dell's R660xs Technical Guide does not tie the 96 GB module to a processor generation — it states the 1, 6 and 8 DIMMs-per-processor rule without qualifying it that way.

Most published specifications for this machine still say 1 TB. That figure is sixteen slots times 64 GB — the ceiling before Dell qualified the 96 GB module — and it has simply not been updated. Speed is a separate question: Dell's specification sheet gives the xs sixteen DIMMs at up to 5200 MT/s, with the actual bus running at 5200, 4800, 4400 or 4000 MT/s depending on the system profile, the processor's maximum and the DIMM's maximum. A machine fitted with entry-level processors will report a lower number than the platform supports — that is a processor limit, not a platform limit.

Dell sells the R660 from a cart. It sells the R660xs only through Contact Sales

Three pages, one product family, one generation, and two different commercial postures — and the cost-optimized machine is the one you cannot buy from a page. You can check all three in under a minute.

How Dell sells each machine on its own store, checked on Dell's US shop pages

Dell's own shop page	How Dell sells it
PowerEdge R660	Configurable, with an Add to Cart button
PowerEdge R660xs	No cart at all. Contact Sales.
PowerEdge R670 (17th generation)	Configurable, with an Add to Cart button

The generation that succeeds the R660 is sold self-serve. The generation the R660 belongs to is sold self-serve. The variant sitting between them is not. That is not a statement about how alive the platform is — Dell is plainly still taking orders for all three — it is a statement about how Dell has decided each machine gets specified.

That explains something buyers often read as evasion. The R660xs is a machine that gets specified in conversation, and that is how the manufacturer itself sells it. We follow the same shape: the R660 is fully configurable on our site, and for the R660xs you tell us the chassis you need — 4 × 3.5-inch, 8 × 2.5-inch or 10 × 2.5-inch — along with the processors, memory and storage, and we specify the rest with you.

One caution applies to any configurator, ours included: the options a web page offers are not the same thing as the combinations Dell supports. Dell's platform ceiling for the R660xs is 250 W per processor. If a configuration tool lets you attach a 300 W or 350 W part to that chassis, the tool is wrong, not Dell. The rest of this guide is about platform rules, because those hold regardless of where you buy.

What one rack unit costs you on the Dell R660

A 1U R660 gives you the same two sockets, the same 32 DDR5 slots and the same 8 TB memory ceiling as the 2U machines in its generation — and then caps you at three PCIe slots, three 75 W single-width GPUs, and a chassis 50.77 mm deeper than the R650 it replaces. Density is the product. These are its consequences, and no specification sheet frames them as a decision.

You can have three PCIe slots, or you can have Gen5 slots, but the third slot is a Gen4 slot. Dell's Technical Guide states it as "Up to three PCIe slots — 2 x PCIe Gen5 slots · 3 x PCIe Gen4 slots." Pages that publish "three PCIe Gen5 slots" have merged two different claims. If your plan needs Gen5 bandwidth on a third card, the R660 is not the chassis.

Rear drive bays are a riser decision, not a chassis decision. Dell documents ten PCIe riser configurations for the R660, and only two of them support rear storage. If a listing advertises the rear 2-bay option, the riser is what makes it true — ask which one is fitted.

Why the R660 tops out at three 75 W single-width GPUs

Dell's ceiling for the R660 is three 75 W single-width cards, and the third one is conditional on the processor you fit. Dell's PowerEdge R660 Technical Guide gives it one line — "GPU Options: Up to 3 x 75 W SW" — and the R660 specification sheet repeats it: "Support for GPUs including 3 x single-wide for workloads requiring acceleration." Three slots, 75 watts each, single-width only.

Seventy-five watts is the slot's own power budget, which puts the eligible parts in the low-profile, bus-powered class. Dell's thermal table for this platform is titled "Thermal restriction for L4 GPU," and its notes are written around that card. A double-width card does not fit under a 1U lid, and Dell's GPU entry for the R660 stops at 75 W with nothing listed above it.

GPU restrictions on the Dell PowerEdge R660, from the Technical Guide's L4 GPU thermal restriction table and its ASHRAE environment lists

Configuration	What Dell supports
Two cards, three low-profile slots	"No additional thermal restriction to support 2x L4 GPUs in slot 1 and slot 2, and non-GPU card in slot 3"
Three cards	"For 3x LPs configuration with 3x L4 GPU cards, it requires additional CPU SKUs to support restriction"
Three cards, no backplane or 8 × 2.5-inch	"CPU TDP higher than 270 W are not supported"
Three cards, 10 × 2.5-inch or 16 × EDSFF E3.S	"CPU TDP higher than 225 W are not supported"
Any card count, ASHRAE A3 or A4 room	"GPU is not supported"
R660xs	No GPU row in its Technical Guide at all

The third card is paid for in processor headroom. An 8-bay R660 that takes a 350 W processor with none fitted drops to 270 W with three cards; a 10-bay or 16-bay E3.S chassis drops to 225 W, and to 205 W with two 2.5-inch rear drives. Two cards cost nothing and leave slot 3 for a network or storage card. The third also depends on the riser: Dell lists one of its ten riser configurations twice, in a GPU variant and a non-GPU variant. Ask which is fitted before you count on that slot.

A warm room removes GPU support outright. Dell's restriction list for ASHRAE Category A3 — 5 to 40 °C (41 to 104 °F) — reads "GPU is not supported," with no card count and no exception. Category A4 repeats it. That is a room question, not a configuration question, and cheaper to answer before the purchase order than after the rails are in.

Our builder is narrower than the platform here, and it is worth saying so: the R660 configurator on this site has no graphics-card option group. A GPU R660 is not something you can click together. The machines we configure with graphics-card options are 2U — the Dell PowerEdge R750xa for accelerator density, the Dell PowerEdge R760 for a general-purpose build. If a 1U accelerated build is genuinely the requirement, talk to us about it. Card-by-card selection sits outside this guide: see which GPU belongs in which PowerEdge.

The chassis you choose caps the processor you can fit

The more drives you put in the front of an R660, the less processor you can put in the back. This is not thermal headroom advice — it is a supported-configuration rule, and Dell publishes it as a table of restrictions by chassis. The figures below are for ASHRAE Category A2, which Dell defines as 10 to 35 °C (50 to 95 °F): an ordinary data-centre room, not an edge case.

Processor TDP ceilings by chassis in an ASHRAE A2 room, from Dell's PowerEdge R660 Technical Guide

R660 configuration	Processor TDP ceiling, ASHRAE A2
No backplane (0-drive)	Above 350 W not supported; above 300 W, 30 °C maximum
8 × 2.5-inch	Above 350 W not supported; above 300 W, 30 °C maximum
10 × 2.5-inch	Above 300 W not supported
10 × 2.5-inch with rear drives	Above 270 W not supported
10 × 2.5-inch with 256 GB RDIMMs	Above 250 W, 30 °C maximum
10 × 2.5-inch with rear drives and 256 GB RDIMMs	Above 225 W, 30 °C maximum

Read the 350 W headline in that light. Dell's own specification sheet pairs it explicitly with a chassis: "Support for up to 8 x 2.5" drives and 2 x 350 watt processors." A 10-bay R660 specified around a 350 W processor is a configuration Dell does not support, and no fan grade changes that. Pick the chassis and the processor together, in that order.

A warmer room removes capability rather than just headroom. At ASHRAE Category A3, which Dell defines as 5 to 40 °C (41 to 104 °F), the R660 no longer supports processors above 185 W in the 10-bay chassis or above 205 W in the 8-bay and no-backplane chassis — and it also loses 128 GB and larger RDIMMs, 2.5-inch NVMe in the 8- and 10-bay configurations, rear drives, and GPUs entirely. Peripheral cards above 25 W are unsupported, two power supplies become mandatory, and Dell requires 85 °C active optics cables. If the destination runs warm, check the class before you check anything else.

Check your rack depth before you buy

The R660 is 50.77 mm — two inches — deeper than the R650 it replaces, on both measurements. Dell's Technical Guide gives both machines in the same table: the R660 at 809.04 mm (31.85 in) without bezel and 822.88 mm (32.39 in) with, against the R650 at 758.27 mm (29.85 in) and 772.11 mm (30.39 in). Height (42.8 mm) and width (482 mm) are unchanged.

Dell's chassis table gives the 8-bay and 10-bay R660 at 751.47 mm from the mounting ear to the rear wall; the R660xs is shallower again at 677.1 mm. A cabinet that comfortably held R650s may not close on R660s once rear PDU and cable management are accounted for. Measure the usable depth before the rails arrive, not after.

Dell PowerEdge R660 specifications, verified against Dell's technical guide

The Dell PowerEdge R660 is a two-socket 1U server with 32 DDR5 slots, an 8 TB memory ceiling, up to three PCIe slots and a 350 W processor ceiling that depends on the chassis. Every row below is quoted from Dell's 76-page December 2024 PowerEdge R660 Technical Guide (Regulatory Model E83S) or its specification sheet. Where a figure depends on which processor generation is installed, both answers are given — that dependency is the single reason published Dell R660 specs disagree with each other.

Dell PowerEdge R660 specifications, from Dell's Technical Guide (Regulatory Model E83S) and specification sheet

Specification	Value
Form factor	1U rack server, two sockets
Processors	Up to two 4th Generation Intel Xeon Scalable or Intel Xeon Max processors, up to 56 cores each; or up to two 5th Generation Intel Xeon Scalable processors, up to 64 cores each
Maximum processor TDP	350 W — subject to the chassis restrictions above
UPI links	Up to four per processor; 12.8 / 14.4 / 16 GT/s on 4th Generation, adding 20 GT/s on 5th Generation
PCIe lanes	80 lanes of PCIe 5.0 per processor at 32 GT/s
Memory	32 DDR5 DIMM slots, RDIMM 8 TB maximum
Memory speed	Up to 4800 MT/s (4th Generation) or 5600 MT/s (5th Generation) at one DIMM per channel; 4400 MT/s at two DIMMs per channel
PCIe slots	Up to three: two Gen5, or three Gen4
Storage controllers	PERC H965i, H755, H755N, H355 internal; H965e external; HBA355i, HBA355e, HBA465i non-RAID; S160 software RAID
Boot	BOSS-N1, M.2 NVMe
GPU	Up to three 75 W single-width
Cooling	Air, or optional direct liquid cooling
Dimensions	42.8 mm H × 482 mm W × 809.04 mm D without bezel (822.88 mm with)

The 8 TB memory ceiling and the 5600 MT/s memory speed are not available at the same time. Dell's supported-DIMM matrix lists 256 GB octal-rank modules at 4800 MT/s only; the fastest 5600 MT/s modules top out at 128 GB. Thirty-two 256 GB modules gets you 8 TB at 4800 MT/s rated speed; thirty-two 128 GB modules gets you 4 TB at 5600 MT/s. Capacity and bandwidth are a trade on this platform, and populating two DIMMs per channel drops the bus to 4400 MT/s either way. The general DDR5 population rules for this generation — rank matching, channel filling, why eight identical modules per processor is the unit of population — are covered in the Dell PowerEdge R760 buying guide; they apply unchanged here. DDR5 server memory is a line item on any move up from 14th- or 15th-generation hardware, not a carry-over.

The processor choice is the same 4th-versus-5th-Generation decision the R760 guide sets out, with one 1U twist: here it is made jointly with the drive-bay count, because of the TDP restrictions above. A part that would be the obvious pick in 2U may not be supported in a 10-bay 1U machine. We stock both generations alongside Intel Xeon Max parts — see Intel server processors — so check the wattage against the chassis, not against the platform.

Is the Dell PowerEdge R660 end of life?

No, and there is no model-level date to look up. Dell does not publish end-of-life or end-of-service-life dates at model level for PowerEdge servers — the lifecycle attaches to the individual machine through its service tag. We set out the full evidence for that, including how to retrieve the only date that applies to a specific server, in the full end-of-life evidence for Dell PowerEdge servers. It is true of every PowerEdge, not just the R640.

The related question people actually type is when the R660 launched, and the honest answer is that the useful information is generational rather than calendrical. The R660 is Dell's 16th-generation 1U platform, built for 4th- and 5th-Generation Intel Xeon Scalable and Intel Xeon Max processors and DDR5 memory, with the 17th-generation R670 shipping alongside it. Dell lists both for sale on its own shop pages. For R660-specific configuration and lifecycle detail, the Dell PowerEdge R660 product page carries the current picture.

Which operating systems Dell lists for the PowerEdge R660

Dell's R660 Technical Guide lists Canonical Ubuntu Server LTS, Microsoft Windows Server with Hyper-V, Red Hat Enterprise Linux, SUSE Linux Enterprise Server and VMware ESXi. That is Dell's list of what the platform is supported on, and it is the right starting point — but it is not where certification actually lives.

Certification itself is maintained by the operating-system vendors rather than by Dell or the reseller, and their lists are updated continuously. Red Hat publishes the PowerEdge R660's certification record in the Red Hat Ecosystem Catalog — the live source to check for the specific release you are deploying. Any version list republished on a reseller page, including this one, is a snapshot; the catalog is the record.

On the secondary market that produces a reassuring answer: certification attaches to the platform, not to the seller or the purchase order. A refurbished R660 carries the same operating-system certifications as a new one, because the certification was granted against the hardware. What does not transfer is anything licensed — a separate question from what is certified. If the machine is destined for a Proxmox host, sizing is covered in our Proxmox hardware requirements guide.

What to check before you buy a used Dell PowerEdge R660

Most of what goes wrong with a used Dell R660 is knowable before it ships. The generation-level checks for 16th-generation hardware — iDRAC9 licence generation and service-tag binding, PERC versus non-RAID HBA, DDR5 rank and speed matching — are in the full 16th-generation pre-purchase checklist and apply identically here. These are the ones specific to one rack unit.

1. Rack depth. 809.04 mm without bezel, 50.77 mm more than an R650. Measure the cabinet, including rear PDU and cable management, before it ships.
2. Chassis and processor together, against the room. A 10-bay machine caps at 300 W, or 270 W with rear drives, in a standard 10–35 °C room, and lower again in an A3 environment. Confirm the installed processors are supported in the chassis they arrived in and in the room they are going to — not just on the platform.
3. Which backplane is fitted. The 8-bay, 10-bay and E3.S chassis are different machines underneath. NVMe capability is bounded by the backplane, not by the drives you buy afterwards.
4. Which riser configuration is fitted. It decides how many slots you have, whether any of them are Gen5, and whether rear drives are possible at all — only two of Dell's ten riser configurations support rear storage.
5. The boot module. 16th-generation machines use BOSS-N1 with M.2 NVMe. A BOSS-S1 or S2 is a SATA module from the previous generation.
6. Listings that name 15th-generation parts. A "16th-generation" R660 described with BOSS-S1/S2, PERC H745 or H345, or S150 software RAID is quoting R650-era components. Dell notes that H355 replaced H345 as the entry RAID controller from December 2021 and that H345 was deprecated in January 2022.
7. Which processor generation is installed. On an R660xs it decides the core ceiling in the opposite direction to the R660 — 32 cores on 4th Generation, 28 on 5th — which is the one place in this family where the newer part is the smaller one.

Every server we sell goes through this process in our own receiving area before it is listed, which is why our R660 photography shows the actual machines rather than manufacturer renders. If you are buying elsewhere, the list is still the list.

Frequently Asked Questions

Which 16th-generation 1U PowerEdge supports 3.5-inch drives?

The Dell PowerEdge R660xs, and only the R660xs. Dell's R660xs Technical Guide lists a 4 × 3.5-inch SAS/SATA front chassis with a 96 TB maximum, alongside 8-bay and 10-bay 2.5-inch options. The full-featured R660 has no 3.5-inch option at all — its Technical Guide lists 8 × 2.5-inch, 10 × 2.5-inch and 14 or 16 × EDSFF E3.S, and the only mention of "3.5-inch" in that 76-page document describes the previous-generation R650.

How much memory does the Dell PowerEdge R660xs support?

1.5 TB, with both processors installed and all sixteen slots filled with 96 GB RDIMMs. Dell's R660xs Technical Guide (Regulatory Model E87S, revision A04) states "16 DDR5 DIMM slots … Supports RDIMM 1.5 TB max." The largest RDIMM Dell supports on this platform is 96 GB, and 96 GB modules are supported only at 1, 6 or 8 DIMMs per processor, with matching populations on both processors — so the ceiling is eight modules per processor across two processors. Dell's R660xs guide does not gate the 96 GB module on processor generation. The 1 TB figure still carried by most published specifications is sixteen slots times 64 GB, the ceiling before Dell qualified the 96 GB module.

Will a Dell PowerEdge R660 fit a rack sized for an R650?

Only if the cabinet has two inches of depth to spare — the R660 is 50.77 mm deeper than the R650 on both measurements. Dell's R660 Technical Guide gives the R660 as 809.04 mm (31.85 in) without bezel and 822.88 mm (32.39 in) with bezel, against the R650's 758.27 mm and 772.11 mm in the same table. Height (42.8 mm) and width (482 mm) are unchanged. Check the rear-door clearance with PDU and cable management in place before you commit.

How many PCIe slots does the Dell PowerEdge R660 have?

Up to three, but not three of the same generation. Dell's Technical Guide specifies two PCIe Gen5 slots or three PCIe Gen4 slots — the third slot costs you Gen5. Rear drive bays are also a riser decision rather than a chassis decision: of Dell's ten documented riser configurations, only two support rear storage.

Can the Dell PowerEdge R660 run GPUs?

Yes — up to three 75 W single-width cards. Dell's R660 Technical Guide lists "GPU Options: Up to 3 x 75 W SW." Two cards carry no additional restriction. Three require specific processor SKUs and cap CPU TDP at 270 W in the no-backplane and 8 × 2.5-inch chassis, 225 W in the 10 × 2.5-inch and 16 × EDSFF E3.S chassis. In an ASHRAE A3 or A4 room Dell supports no GPU, and the R660xs has no GPU option. Double-width cards need 2U.

What is the maximum processor TDP the Dell PowerEdge R660xs supports?

250 W, for both 4th and 5th Generation Intel Xeon Scalable processors, per Dell's R660xs Technical Guide. The full-featured R660 supports up to 350 W. The 250 W ceiling is why the R660xs tops out at 32 cores per socket with 4th Generation processors and 28 cores with 5th Generation — the higher-core-count 5th Generation parts exceed the envelope.

Can a 10-bay Dell PowerEdge R660 take the highest-TDP processors?

No. In a standard ASHRAE A2 environment, which Dell defines as 10 to 35 °C, Dell does not support processors above 300 W in the 10 × 2.5-inch configuration, or above 270 W when rear drives are fitted. The 350 W parts are supported in the 8 × 2.5-inch and no-backplane configurations — Dell's own specification sheet pairs them explicitly: "Support for up to 8 x 2.5" drives and 2 x 350 watt processors." Choose the chassis and the processor together.

Does the Dell PowerEdge R660xs support E3.S NVMe drives?

No. Dell's 84-page R660xs Technical Guide contains no reference to E3.S or EDSFF drives. E3.S is an R660 capability within this family — the R660 supports 14 or 16 front E3.S Gen5 drives, up to 204.8 TB, plus up to two at the rear. If you need EDSFF density in one rack unit, the R660 is the machine; if you need 3.5-inch nearline capacity in one rack unit, the R660xs is.

Why do published specifications disagree on whether the R660 has 56 or 64 cores?

Because both figures are right, for different processors. Dell's R660 Technical Guide specifies up to two 4th Generation Intel Xeon Scalable or Intel Xeon Max processors with up to 56 cores each, or up to two 5th Generation Intel Xeon Scalable processors with up to 64 cores each. The same split applies to memory speed: 4800 MT/s at one DIMM per channel with 4th Generation, 5600 MT/s with 5th Generation. A specification that gives one number without naming the processor generation is incomplete rather than wrong.

Which operating systems does Dell list for the PowerEdge R660?

Dell's R660 Technical Guide lists Canonical Ubuntu Server LTS, Microsoft Windows Server with Hyper-V, Red Hat Enterprise Linux, SUSE Linux Enterprise Server and VMware ESXi. Certification itself is maintained by the operating-system vendors rather than by Dell or the reseller, and the authoritative live lists sit with them — Red Hat publishes the PowerEdge R660's certification record in its Ecosystem Catalog. Because certification attaches to the platform, a refurbished R660 carries the same certifications as a new one.

Where to go from here

If the drive plan is 2.5-inch or E3.S, you can configure a Dell PowerEdge R660 to your specification — pick the chassis first, then the processors against that chassis's TDP ceiling. If it is 3.5-inch, the Dell PowerEdge R660xs is the one machine in this generation and form factor that takes them, and we will specify it with you. To compare across the range, browse refurbished Dell PowerEdge servers.

Our R660-family catalog is deliberately narrow: two configurable servers — the R660 and the R660xs — plus ten R660-specific spare parts and a further set of components shared with other 16th-generation models. If you need a part rather than a machine, tell us the Dell part number and we will tell you whether it is on the shelf.