The ThinkSystem SR645 V3 fits two AMD EPYC 9004 or 9005 processors and 24 DDR5 DIMMs in 1U of rack space. It suits virtualisation, VDI and database estates where rack space is the constraint, and this data sheet sets out what that density costs under Lenovo’s rules: cooling modules, inlet-temperature caps, one-processor limits and the 1U options that exclude each other.
Our read of Lenovo’s documentation: where the SR645 V3 is strong, and the limits worth knowing before you spec one.
Strengths
+Two EPYC sockets in one rack unit: a pair of 160-core 9845s gives 320 cores, and each processor drives its own 12 DDR5 channels.
+Three processor-cooling routes — the 1U high-performance heatsink, a sealed Neptune Liquid to Air loop and open-loop Neptune Core water cooling — and Neptune Core accepts every listed processor.
+Storage can be 16 × E1.S NVMe, twelve 2.5-inch bays that all run as direct-attach NVMe, or four 3.5-inch bays for capacity disks.
+A front-I/O chassis moves two PCIe slots and the OCP 3.0 card to the front beside up to four drives, so almost everything except power cabling is worked on from the front.
+Hardware RAID for U.3 NVMe through Tri-Mode RAID 940 adapters, alongside onboard SATA and NVMe ports that need no controller at all.
Watch-outs
!Heat sets the ceiling: 320–400 W processors hold inlet air to 25 °C on the air heatsink (30 °C with the Liquid to Air module), and 240–300 W parts, passive GPUs, rear 2.5-inch drives or 256 GB DIMMs each cap it at 30 °C.
!The eleven 4th Gen SKUs rated 320 W or more come only as factory-built, liquid-cooled, two-processor servers; neither Neptune module can be retrofitted.
!Options compete for 1U space: rear 2.5-inch bays leave only slot 1, 7mm drives occupy slot 3, any GPU forbids rear drives, and choosing front slots removes M.2, the Liquid to Air cooler and the lockable bezel.
!With one processor the server has 12 DIMM slots, no slot 3 or front slots, and none of the 12-NVMe, E1.S or front-slot storage layouts.
!The NVIDIA L4 is the only GPU listed — four at most — and as a Controlled GPU it ships only on Lenovo’s “for AI” base models.
Processors46 SKUs
Cores / CPU8–160
DIMM slots24
Backplanes22
Max bays16
GPUsup to 5
PSU options8 · to 1,800 W
02 — Processors
46 supported processors, mapped
Lenovo lists 46 EPYC processors for the SR645 V3: 25 from the 5th Gen 9005 family (Zen 5, plus the core-dense Zen 5c parts) and 21 from the 4th Gen 9004 family, which includes Genoa-X models with 3D V-Cache and Bergamo. Core counts start at 8 and reach 160, with thermal ratings of 125–400 W. The landscape plots each one; the explorer below sorts and filters the list.
Processor landscape — cores × TDP
46 SKUs · 2 families
AMD EPYC 9005 25AMD EPYC 9004 21Bubble size = L3 cache · hover a bubble for the full SKU
Processor explorer
filter · sort · compare
Processor
Cores / threads
Base
L3 cache
TDP
W / core
Memory
AMD EPYC 9845
160 / 320
2.1 GHz
320 MB
390 W
2.4
DDR5-6400
AMD EPYC 9825
144 / 288
2.2 GHz
384 MB
390 W
2.7
DDR5-6400
AMD EPYC 9745
128 / 256
2.4 GHz
256 MB
400 W
3.1
DDR5-6400
AMD EPYC 9754
128 / 256
2.25 GHz
256 MB
360 W
2.8
DDR5-4800
AMD EPYC 9734
112 / 224
2.2 GHz
256 MB
340 W
3.0
DDR5-4800
AMD EPYC 9655
96 / 192
2.6 GHz
384 MB
400 W
4.2
DDR5-6400
AMD EPYC 9655P
96 / 192
2.6 GHz
384 MB
400 W
4.2
DDR5-6400
AMD EPYC 9645
96 / 192
2.3 GHz
256 MB
320 W
3.3
DDR5-6400
AMD EPYC 9684X
96 / 192
2.55 GHz
1150 MB
400 W
4.2
DDR5-4800
AMD EPYC 9654
96 / 192
2.4 GHz
384 MB
360 W
3.8
DDR5-4800
AMD EPYC 9634
84 / 168
2.25 GHz
384 MB
290 W
3.5
DDR5-4800
AMD EPYC 9565
72 / 144
3.15 GHz
384 MB
400 W
5.6
DDR5-6400
AMD EPYC 9575F
64 / 128
3.3 GHz
256 MB
400 W
6.3
DDR5-6400
AMD EPYC 9555
64 / 128
3.2 GHz
256 MB
360 W
5.6
DDR5-6400
AMD EPYC 9555P
64 / 128
3.2 GHz
256 MB
360 W
5.6
DDR5-6400
AMD EPYC 9535
64 / 128
2.4 GHz
256 MB
300 W
4.7
DDR5-6400
AMD EPYC 9554
64 / 128
3.1 GHz
256 MB
360 W
5.6
DDR5-4800
AMD EPYC 9534
64 / 128
2.45 GHz
256 MB
280 W
4.4
DDR5-4800
AMD EPYC 9475F
48 / 96
3.65 GHz
256 MB
400 W
8.3
DDR5-6400
AMD EPYC 9455
48 / 96
3.15 GHz
256 MB
300 W
6.3
DDR5-6400
AMD EPYC 9455P
48 / 96
3.15 GHz
256 MB
300 W
6.3
DDR5-6400
AMD EPYC 9474F
48 / 96
3.6 GHz
256 MB
360 W
7.5
DDR5-4800
AMD EPYC 9454
48 / 96
2.75 GHz
256 MB
290 W
6.0
DDR5-4800
AMD EPYC 9454P
48 / 96
2.75 GHz
256 MB
290 W
6.0
DDR5-4800
AMD EPYC 9365
36 / 72
3.4 GHz
192 MB
300 W
8.3
DDR5-6400
AMD EPYC 9375F
32 / 64
3.8 GHz
256 MB
320 W
10.0
DDR5-6400
AMD EPYC 9355
32 / 64
3.55 GHz
256 MB
280 W
8.8
DDR5-6400
AMD EPYC 9355P
32 / 64
3.55 GHz
256 MB
280 W
8.8
DDR5-6400
AMD EPYC 9335
32 / 64
3 GHz
128 MB
210 W
6.6
DDR5-6400
AMD EPYC 9374F
32 / 64
3.85 GHz
256 MB
320 W
10.0
DDR5-4800
AMD EPYC 9384X
32 / 64
3.1 GHz
768 MB
320 W
10.0
DDR5-4800
AMD EPYC 9354
32 / 64
3.25 GHz
256 MB
280 W
8.8
DDR5-4800
AMD EPYC 9354P
32 / 64
3.25 GHz
256 MB
280 W
8.8
DDR5-4800
AMD EPYC 9334
32 / 64
2.7 GHz
128 MB
210 W
6.6
DDR5-4800
AMD EPYC 9275F
24 / 48
4.1 GHz
256 MB
320 W
13.3
DDR5-6400
AMD EPYC 9255
24 / 48
3.25 GHz
128 MB
200 W
8.3
DDR5-6400
AMD EPYC 9274F
24 / 48
4.05 GHz
256 MB
320 W
13.3
DDR5-4800
AMD EPYC 9224
24 / 48
2.5 GHz
64 MB
200 W
8.3
DDR5-4800
AMD EPYC 9254
24 / 48
2.9 GHz
128 MB
200 W
8.3
DDR5-4800
AMD EPYC 9175F
16 / 32
4.2 GHz
512 MB
320 W
20.0
DDR5-6400
AMD EPYC 9135
16 / 32
3.65 GHz
64 MB
200 W
12.5
DDR5-6400
AMD EPYC 9115
16 / 32
2.6 GHz
64 MB
125 W
7.8
DDR5-6400
AMD EPYC 9174F
16 / 32
4.1 GHz
256 MB
320 W
20.0
DDR5-4800
AMD EPYC 9184X
16 / 32
3.55 GHz
768 MB
320 W
20.0
DDR5-4800
AMD EPYC 9124
16 / 32
3 GHz
64 MB
200 W
12.5
DDR5-4800
AMD EPYC 9015
8 / 16
3.6 GHz
64 MB
125 W
15.6
DDR5-6400
The six P-suffix parts (9355P, 9455P, 9555P, 9655P, 9354P, 9454P) are single-socket processors, sold only in factory (CTO) or preconfigured builds rather than as option kits.
Sixteen SKUs are listed for two-processor servers only: all five 5th Gen F-suffix parts and every 4th Gen part rated 320 W or more. Those eleven 4th Gen parts also require liquid cooling and cannot be added as field upgrades.
Inlet-air limits by TDP: 25 °C for 320–400 W on the standard heatsink, 30 °C above 240 W up to 300 W, 35 °C for 200–240 W and 45 °C at 200 W or less. A 200 W part falls under both of the last two rules as Lenovo words them.
Standard fans are allowed only with processors of 240 W or less, no more than eight front SAS/SATA drives, and no GPUs, NVMe drives, 256 GB 3DS RDIMMs, 100Gb-plus adapters or Broadcom 57454 OCP card; anything else takes the Performance fans. With Neptune Core water cooling, Lenovo permits Standard fans in most configurations.
All 25 5th Gen processors reach 6400 MHz memory only with Lenovo’s listed 6400 MHz DIMMs and current firmware, falling back to 6000 MHz otherwise. The 4th Gen ceiling is 4800 MHz.
Platform Secure Boot is enabled at the factory unless feature C18D is chosen; once enabled, a processor is cryptographically tied to this server’s firmware signing key and can afterwards run only on system boards that use the same key.
03 — Memory
24 DIMM slots, 12 per processor
Each processor has 12 DDR5 channels and takes exactly one DIMM per channel, so a two-processor server has 24 slots and a one-processor server 12. Lenovo supports 1, 2, 4, 6, 8, 10 or 12 DIMMs per processor. Reaching 6 TB takes 24 of the 256 GB 3DS modules, and Lenovo lists that module against 5th Gen processors alone.
Capacity with every slot filled
by DIMM size
Rated memory speed
from the processor table
Processor family
Up to
AMD EPYC 9005
6400 MT/s
AMD EPYC 9004
4800 MT/s
On 4th Gen processors Lenovo’s biggest listed module is 128 GB, capping those servers at 3 TB (24 × 128 GB). That module is rated 5600 MHz yet clocks at 4800 MHz here.
Memory rated 4800 MHz works only with 4th Gen processors and 6400 MHz memory only with 5th Gen, where it runs at 6000 or 6400 MHz.
No mixing of DIMM types (9x4 with 10x4), DRAM densities (16Gb, 24Gb, 32Gb), x4 with x8 modules, or 128 GB with 256 GB 3DS RDIMMs; each processor accepts at most two DIMM capacities.
Memory mirroring and rank sparing are not supported, and SDDC (Chipkill) covers x4 DIMMs but not 9x4 RDIMMs. UDIMMs, LRDIMMs and persistent memory are not supported.
Density has a thermal price: any 256 GB DIMM limits inlet air to 30 °C, forces the Performance fans and rules out the Neptune Liquid to Air module.
04 — Storage
22 backplane options, up to 16 bays
The front of the chassis takes one of three bay types — up to ten 2.5-inch bays, sixteen E1.S EDSFF bays or four 3.5-inch bays — and the rear can add two 2.5-inch or two 7mm drives. Up to two M.2 drives sit inside. The headline layouts below come from Lenovo’s storage configuration tables; the 4 × 3.5-inch chassis is covered in the notes.
Headline layouts
front panel view
Front panel
Rear module
Configs 28A and 28AH: a ten-bay NVMe backplane (Gen4 or Gen5) plus a two-bay rear NVMe module, all twelve drives on onboard NVMe ports with an x4 link each. Two processors are required, and the rear bays leave slot 1 as the only PCIe slot.
SAS/SATANVMeSAS/SATA + NVMe
Controllers & boot
On Board SATA AHCI Mode — Onboard (no RAID). Onboard controllers; RAID levels: None
Non RAID NVMe — Onboard (no RAID). Onboard controllers; RAID levels: None
ThinkSystem 440-16e SAS/SATA PCIe Gen4 12Gb HBA — HBA. External SAS HBA (JBOD to external enclosures/tape), part 4Y37A09724 feature B8P7 - lp1607 L3919
The 3.5-inch chassis takes four SAS/SATA drives on the 4 × 3.5-inch backplane; the NVMe-capable 3.5-inch backplanes (BS7L, B8N1) are now marked withdrawn. Two rear 2.5-inch bays can be added (six drives), and the basic four-bay layout runs with one or two processors on the onboard SATA ports.
Onboard ports connect up to twelve NVMe drives (x4 each) and twelve SATA drives without an adapter; NVMe retimer adapters extend NVMe further, again without oversubscription.
Tri-Mode lets a RAID 940 adapter mix U.3 NVMe with SAS and SATA drives, but only on AnyBay backplanes, over a single PCIe lane per NVMe drive, and never with U.2 drives; factory builds switch it on with feature CH5Z.
Choosing the two rear 2.5-inch bays costs slots 2 and 3 as well as any GPU; the 7mm pair instead sits in slot 3 and likewise excludes GPUs. Lenovo offers the 7mm pair without RAID, with Marvell NVMe RAID, or with Broadcom RAID for SATA or NVMe.
M.2 and 7mm boot drives can be combined only in the pairings Lenovo lists, and M.2 is unavailable with front slots or the Neptune Liquid to Air module.
Every documented backplane
19 with drive bays
2.5-inch3.5-inchEDSFF (E1.S / E3.S)
05 — Accelerators & I/O
GPUs, PCIe and networking
Lenovo lists a single GPU for the SR645 V3: the 72 W NVIDIA L4 24GB, up to four per server. Two go in rear slots 1 and 3 and the rest in front slots 4 and 5, each on a specific riser. Every GPU fitted must be identical, and a GPU server gives up rear drive bays and flash storage adapters, needs the Performance fans and is held to 30 °C inlet air. Up to 4 × NVIDIA L4 per Lenovo’s GPU table; its summary tables quote up to five single-width GPUs of 75 W.
NVIDIA L4 24GB PCIe Gen4 Passive GPU
single-wide
24GB · up to 4
I/O topology
64 lanes per CPU
Each EPYC processor brings 12 DDR5 channels and 128 PCIe 5.0 lanes — Lenovo puts 64 of them at the disposal of slots and NVMe drives — and four dedicated xGMI x16 links tie the pair together. Riser 1 (slots 1 and 2) belongs to CPU 1, while slot 3 and the two front slots are wired to CPU 2.
Rear slot layouts: three low-profile x16 slots; one low-profile plus one full-height slot, both on CPU 1 or split across the two processors; one slot plus two rear 2.5-inch drives; or two slots plus two 7mm drives.
Configuring the front slots disconnects the rear OCP slot — the server holds one OCP adapter in total.
With Neptune Core water cooling the loop runs through the slot 2 space, leaving slots 1 and 3, or slot 1 with 7mm drives in slot 3.
With 2.5-inch front bays, a cabled CFF RAID adapter or HBA occupies its own internal space on a PCIe 4.0 x8 connector instead of a slot.
06 — Power & cooling
8 power supplies, 750–1,800 W
Eight hot-swap supplies appear in Lenovo’s table — Titanium 750 W (two versions), 1100 W and 1800 W; Platinum 750 W, 1100 W and 1800 W; and one 1100 W unit fed from −48 V DC. A server takes one or two, and a pair must match.
AC−48 V DC
The table marks 110 V AC input only on the 750 W and 1100 W Platinum supplies, while a note beneath it calls every supported supply dual-voltage; we work to the table. Low-line (100–127 V) use of the 1100 W unit calls for a cable rated over 10 A.
The summary and generation-comparison tables still mention a 500 W supply that the ordering table no longer includes.
All AC units have a C14 inlet; the DC supply wants −48 to −60 V and is rated at 26 A inlet current.
Measured from the rack flange, the PSU handles reach 754 mm on 1100 W-or-smaller supplies and 782 mm on the 1800 W models.
Cooling: six 40 mm dual-rotor hot-swap fans with one processor, eight with two, N+1 rotor redundancy, plus a fan in each supply. Standard fans spin to 21K RPM, Performance fans to 28K RPM.
07 — Management, security & OS
Run it, secure it, choose the OS
Management
XClarity Controller 2 (XCC2) on an ASPEED AST2600 BMC
Rear 1GbE management port · optional second XCC2 port on an OCP adapter
No power capping on the SR645 V3, even with Platinum
IPMI 2.0 (IPMI-over-LAN off by default), SNMPv3, CIM-XML, Redfish
XClarity Provisioning Manager (F1 at boot)
XClarity One cloud management, licensed per endpoint
XClarity Essentials: OneCLI, UpdateXpress, Bootable Media Creator
XClarity Energy Manager (licence included with Platinum) · Lenovo Capacity Planner
Front diagnostics port for the External Diagnostics Handset · XClarity One Mobile over USB
Security
AMD Platform Secure Boot, enabled by default (C18D ships it disabled)
AMD Secure Root-of-Trust, Secure Run and Secure Move
Platform Firmware Resiliency hardware Root of Trust
Integrated TPM 2.0 · Nationz TPM 2.0 in China (CTO only)
UEFI Secure Boot for signed operating systems
System Guard component-change monitoring (XCC2 Platinum)
Self-encrypting drives with enterprise key managers such as IBM SKLM
NIST SP 800-147B compliant · firmware signing to FIPS and NIST requirements
Optional intrusion switch and lockable bezel (bezel not with front PCIe slots)
Operating systems
Microsoft Windows Server 2019, 2022 and 2025
Windows 10 and 11 (workstation base models; subset of adapters and drives)
Red Hat Enterprise Linux 8.10, 9.4–9.8 and 10.0–10.2 (5th Gen); from 8.6 with 4th Gen
SUSE Linux Enterprise Server 15 SP6, SP7 and 16 (5th Gen); from 15 SP4 with 4th Gen
Ubuntu 22.04, 24.04 and 26.04 LTS; 20.04 with 4th Gen only
VMware ESXi 8.0 U3, 9.0 and 9.1 (5th Gen); from 7.0 U3 with 4th Gen · factory preload, not with NVIDIA GPUs
08 — Compare
SR645 → SR645 V3
Lenovo’s guide sets the V3 against the SR645 it replaced. Cores, PCIe generation and memory channels all rise, but the move to one DIMM per channel cuts the slot count from 32 to 24 and the memory ceiling from 8 TB to 6 TB.
Previous generationThinkSystem SR645
This modelThinkSystem SR645 V3
Processors
2 × 2nd or 3rd Gen EPYC · up to 64 cores · 280 W
2 × 4th or 5th Gen EPYC · up to 160 cores · 400 W
PCIe lanes per CPU
64 × PCIe 4.0
64 × PCIe 5.0
Processor links
4 × xGMI x16
4 × xGMI x16
Memory
DDR4 to 2933 MHz · 8 channels · 2 DPC
DDR5 to 6400 MHz · 12 channels · 1 DPC
DIMM slots
32
24
Maximum memory
8 TB
6 TB
Front storage
4 × 3.5" (SAS/SATA or AnyBay), 8 or 10 × 2.5"
4 × 3.5", 8 or 10 × 2.5", or 16 × E1.S
PCIe slots
Up to 3, all rear, all Gen4
Up to 5 (3 rear + 2 front), Gen4/Gen5 mix
OCP 3.0
Rear, PCIe Gen4 x16
Rear or front
GPUs
Up to 3 × 75 W
Up to 5 × 75 W
Management
XClarity Controller
XClarity Controller 2
Source: Lenovo Press LP1607 (SR645 V3 product guide), Table 2 — Comparing the ThinkSystem SR645 V3 to the previous generation SR645.
The SR645 V3 family side by side
Lenovo builds this EPYC platform in four V3 shapes. The SR635 V3 is the one-socket 1U counterpart; the SR665 V3 (two sockets) and SR655 V3 (one socket) spend a second rack unit on many more drives and GPUs. The SR630 V3 and SR630 V4 are the Intel Xeon 1U dual-socket alternatives. Bars compare each model’s spec-file limits.
This modelSiblings and successorEach value from that model’s own verified spec file · bars scale per column
Head-to-head comparisons
Every figure on this page, set against the machines buyers weigh it up with.
Five builds that play to the SR645 V3’s density, each assembled from options our configurator allows on this model. Cooling modules, risers and base models are not configurator choices, so we check them against Lenovo’s rules when we quote.
Virtualisation
128-core hypervisor node
Two 64-core EPYC 9535s put 128 cores in 1U, with 1.5 TB spread across all 24 memory channels and ten NVMe drives cabled straight to the processors, so no RAID card or retimer takes a slot. The rear slots stay free for extra networking or an HBA.
2 × AMD EPYC 9535 — 64 cores @ 2.4 GHz, 300 W each
24 × 64 GB TruDDR5 6400 MHz — 1.5 TB, one DIMM per channel
10 × 7.68 TB U.3 NVMe on a 10-bay NVMe backplane (onboard ports)
2 × 480 GB M.2 NVMe boot drives
Broadcom 57504 4 × 25GbE OCP 3.0
2 × 1100 W Titanium hot-swap
VMware ESXi 9.0
Processors above 240 W and any NVMe drive both call for the Performance fans, and a 300 W processor limits inlet air to 30 °C.
For databases licensed per core, the 32-core EPYC 9355 pairs a 3.55 GHz base clock with 256 MB of L3 cache per processor. A RAID 940-8i in Tri-Mode puts eight U.3 NVMe drives under hardware RAID 5, 6 or 10 with a flash-backed cache — Lenovo’s config 29 wiring.
2 × AMD EPYC 9355 — 32 cores @ 3.55 GHz, 280 W each
24 × 64 GB TruDDR5 6400 MHz — 1.5 TB
8 × 3.84 TB U.3 NVMe on a 10-bay AnyBay backplane
RAID 940-8i with 8 GB flash cache, Tri-Mode
2 × 480 GB M.2 NVMe boot drives
Intel E810-DA2 2 × 25GbE OCP 3.0
2 × 1100 W Titanium hot-swap
Windows Server 2025
Tri-Mode needs U.3 drives on an AnyBay backplane and gives each NVMe drive one PCIe lane to the controller. The 280 W processors limit inlet air to 30 °C.
The front-I/O chassis opens slots 4 and 5 beside four NVMe bays, which is how Lenovo reaches four L4 GPUs in one rack unit: two in those front slots and two in rear slots 1 and 3. Mid-range 210 W EPYC 9335 processors and 768 GB of memory complete the node.
2 × AMD EPYC 9335 — 32 cores @ 3 GHz, 210 W each
4 × NVIDIA L4 24GB — rear slots 1 and 3, front slots 4 and 5
The L4 is a Controlled GPU, offered only on Lenovo’s “for AI” base models. GPU servers are limited to 30 °C inlet air, need the Performance fans and cannot use rear drive bays, and front slots rule out M.2, so the OS boots from the front NVMe bays. Lenovo’s ESXi factory preload is not available with NVIDIA GPUs.
Two 160-core EPYC 9845 processors (Zen 5c) give 320 cores per rack unit — the most this chassis offers — fed by all 24 channels and a 200Gb HDR InfiniBand or Ethernet adapter for the cluster fabric.
2 × AMD EPYC 9845 — 160 cores @ 2.1 GHz, 390 W each
At 390 W the 9845 is in Lenovo’s 320–400 W group: 25 °C inlet air on the standard heatsink, 30 °C with the Neptune Liquid to Air module. Neptune Core instead sends processor heat to facility water, but needs a Heavy Duty rack with a 38-port manifold and a CDU, gives up slot 2 and rear 2.5-inch drives, and — like the Liquid to Air module — is factory-fit only. We specify the cooling when quoting.
A single 16-core, 125 W EPYC 9115 runs the four-bay 3.5-inch chassis on the onboard SATA ports — one of the layouts Lenovo supports with one processor. Adding the second socket later brings 12 more DIMM slots and slot 3.
1 × AMD EPYC 9115 — 16 cores @ 2.6 GHz, 125 W
12 × 32 GB TruDDR5 6400 MHz — 384 GB, one DIMM per channel
4 × 20 TB 3.5-inch SATA HDD — 80 TB raw, on onboard SATA
2 × 480 GB M.2 NVMe boot drives
Broadcom 57416 2 × 10GBASE-T OCP 3.0
2 × 750 W Titanium hot-swap
Windows Server 2025
Platform Secure Boot is on by default, so a processor added in the field becomes bound to this server once powered on. A 125 W processor on its own would allow 45 °C inlet air, but the M.2 NVMe boot drives bring the limit to 35 °C.
Lenovo ThinkSystem isn’t in our refurbished configurator, and it has no dual-socket 1U AMD model, so the nearest re-certified alternatives are two dual-socket Intel 1U servers and a single-socket EPYC 1U. All three are DDR4-era platforms.
Gen10 Plus · re-certified
HPE ProLiant DL360 Gen10 Plus
1U · two sockets (3rd Gen Xeon)
32 DIMM slots · up to 8 TB DDR4
Up to 10 × SFF / NVMe
DDR4-3200 · PCIe 4.0 · iLO 5
Keeps two processors per rack unit, and its 32 DIMM slots give more memory headroom than the SR645 V3’s 24 — for virtualisation and VDI refreshes.
Internal M.2 (one or two drives) and 2 × rear 7mm, in listed combinations
Controllers
Onboard SATA and NVMe · RAID 540 / 940 (up to 8 GB flash) · 440 HBAs · NVMe retimer
Expansion & networking
PCIe slots
Up to 5: 3 rear x16 + 2 front (LP x8, FHHL x8 or x16)
OCP
1 × OCP 3.0 SFF — rear PCIe 5.0 x16 or front PCIe 4.0 x16
Internal
Cabled CFF RAID/HBA bay (2.5-inch chassis), PCIe 4.0 x8
CXL
CXL 1.1 ready
Accelerators
GPU
NVIDIA L4 24GB, up to 4 (slots 1, 3, 4, 5); summary tables quote up to 5 single-width
Requirements
“for AI” base models · Performance fans · 30 °C inlet · no rear drive bays
Power
Supplies
Up to two hot-swap, identical
AC Titanium
750, 1100 and 1800 W (220 V AC)
AC Platinum
750 and 1100 W (110 V / 220 V AC) · 1800 W (220 V AC)
DC
1100 W, −48 to −60 V DC
Ports & video
Front
1 × USB 3.2 G1 · 1 × USB 2.0 (also XCC) · external diagnostics port · optional VGA
Rear
3 × USB 3.2 G1 · VGA · 1GbE XCC management port · optional DB-9 serial
Internal
1 × USB 3.2 G1
Video
16 MB, integrated in XCC2 · up to 1920 × 1200 at 60 Hz
Environment & warranty
ASHRAE
Class A2 in most configurations; A3, A4 or H1 depending on configuration
Inlet temperature
A2 10–35 °C; configuration caps of 25, 30, 35 or 45 °C
Maximum altitude
3,050 m
Warranty
1 or 3 years by machine type · customer-replaceable units and onsite, 9 × 5 next business day
12 — FAQ
SR645 V3 questions, answered from the documentation
What is the maximum memory of the Lenovo ThinkSystem SR645 V3?
Twenty-four slots filled with 256 GB 3DS RDIMMs make 6 TB. That module is listed only for 5th Gen EPYC; a 4th Gen server tops out at 3 TB because its largest DIMM option is 128 GB. With one processor fitted, only 12 slots are usable.
Which processors does the SR645 V3 support?
Lenovo lists 46 AMD EPYC models, 25 of them 5th Gen 9005 and 21 4th Gen 9004. Core counts run from 8 (EPYC 9015) to 160 (EPYC 9845), and ratings climb as high as 400 W. Six P-suffix chips are single-socket parts, and sixteen more are listed only in pairs.
How is the SR645 V3 cooled with 400 W processors?
The air-cooled 1U High Performance Heatsink is selected automatically according to the configuration, but 4th Gen processors of 320 W or more, including the 400 W 9684X, are supported only with liquid cooling. For those and other hot parts Lenovo offers the Neptune Liquid to Air module, a sealed loop pumping water and glycol to a radiator in front of the fans, and Neptune Core, which carries processor heat to facility water through a rack manifold and coolant distribution unit. Both are factory-fitted only and need two processors.
How many drives does the SR645 V3 hold?
Up to 12 × 2.5-inch drives (10 front, 2 rear), 16 × E1.S NVMe drives at the front, or four 3.5-inch SAS/SATA drives with the option of two rear 2.5-inch bays. All twelve 2.5-inch bays can be NVMe on onboard ports with an x4 link each. Lenovo has withdrawn the NVMe-capable 3.5-inch backplanes, so that chassis gets NVMe only through its rear bays.
Does the SR645 V3 support GPUs?
Lenovo lists one: the 72 W NVIDIA L4 24GB, up to four per server — two in rear slots 1 and 3 and two in the front slots. It is a Controlled GPU offered only on “for AI” base models, and GPU servers lose rear drive bays and are held to 30 °C inlet air. The summary tables quote five single-width GPUs, but the GPU table stops at four L4s.
How many PCIe slots does the SR645 V3 have?
Five at most, plus a single OCP 3.0 position. Slots 1–3 at the rear are x16, and the two factory-only front slots are a low-profile x8 and a full-height x8 or x16. The second processor feeds slot 3 and both front slots, and configuring the front pair disconnects the rear OCP position.
What power supplies are available for the SR645 V3?
Eight hot-swap models: 750 W, 1100 W and 1800 W at 80 PLUS Titanium (the 750 W in two versions) or Platinum, plus a −48 V DC 1100 W unit. Only the Platinum 750 W and 1100 W carry a 110 V AC tick in Lenovo’s table. A pair must be identical.
How big and heavy is the SR645 V3?
The chassis measures 440 × 43 × 773 mm (width, height, depth), or 482 mm wide at the EIA flanges, and weighs at most 20.2 kg. Leave 754 mm behind the rack flange for the handles of 1100 W-class supplies, 782 mm for the 1800 W ones. Neptune Core servers go in Lenovo’s 42U or 48U Heavy Duty Rack Cabinet with a rear water manifold.
Should I choose the SR645 V3, the SR635 V3 or the SR665 V3?
The SR635 V3 is the single-socket 1U: one EPYC, 12 DIMM slots, 3 TB, up to four single-width GPUs and no 3.5-inch bays. The SR665 V3 is the 2U two-socket model: memory matches at 24 DIMMs and 6 TB, but it takes up to 40 × 2.5-inch or 20 × 3.5-inch drives, eight single-width or three double-wide GPUs and up to 12 PCIe slots. The SR645 V3 fits when you need two sockets and rack space counts for more than drive or GPU capacity.
What changed from the SR645 to the SR645 V3?
Processors jump from 2nd/3rd Gen EPYC (64 cores, 280 W) to 4th/5th Gen (160 cores, 400 W); I/O goes to PCIe 5.0 and memory to DDR5 at up to 6400 MHz over 12 channels, and the V3 adds E1.S bays and front slots. Capacity drops from 8 TB to 6 TB because each channel now holds a single DIMM — 24 slots rather than 32.
Is the Lenovo ThinkSystem SR645 V3 end of life?
Not according to Lenovo: the SR645 V3 guide still carries live processor and option tables, with updates marked July 2026, and names no end-of-service date. Coverage follows each machine’s warranty or service contract, and our end-of-life checker logs dates once a manufacturer publishes them.
Specifications are extracted from Lenovo’s published documents and independently re-checked line by line. Configurations are quote-based; availability and exact options are confirmed at quotation. Last reviewed 2026-09-11.
