The ThinkSystem SR635 V3 puts one AMD EPYC 9004 or 9005 processor, up to 160 cores, into a 1U chassis whose twelve DDR5 channels each take a single DIMM. It is for buyers who want dense compute, NVMe or up to four single-width GPUs from one socket, and this data sheet maps its processor thermal limits, drive and slot trade-offs, and when the SR645 V3 or SR655 V3 is the better fit.
Our read of Lenovo’s documentation: where the SR635 V3 is strong, and the limits worth knowing before you spec one.
Strengths
+All twelve DDR5 channels belong to the one processor, so a single socket still reaches 3 TB with 256 GB 3DS RDIMMs, and 5th Gen EPYC can clock that memory at up to 6400 MHz.
+Lenovo lists 45 processors for this chassis, 25 from the 5th Gen and 20 from the 4th Gen EPYC families, running from the 8-core 9015 to the 160-core 9845.
+The onboard NVMe ports can feed sixteen E1.S or twelve 2.5-inch NVMe drives, every one on a full x4 link, with no add-in NVMe adapter to buy.
+For a single rack unit the I/O is flexible: up to three rear and two front PCIe slots, and an OCP 3.0 slot that can be placed at either end.
+High-TDP parts have three cooling routes: the standard performance heatsink, a closed-loop Neptune Liquid to Air module, or the open-loop Neptune Core module, which removes every watt of processor heat through water.
Watch-outs
!Processors of 320 W or more need the closed-loop heatsink or a front cut to four 2.5-inch bays unless the open-loop Neptune Core module is fitted; the 9654 and 9654P are the exception, keeping ten bays at up to 25 °C ambient. The closed-loop module in turn rules out M.2, rear 2.5-inch drives, EDSFF bays, 256 GB DIMMs and CFF adapters.
!There are no 3.5-inch bays and no mid-chassis zone. Twelve drives is the 2.5-inch ceiling, and Lenovo’s configuration tables only reach it with a 10-bay NVMe front plus two rear NVMe bays.
!Rear 2.5-inch bays leave slot 1 as the only PCIe slot and exclude GPUs; with air or closed-loop cooling, rear or EDSFF drives also limit inlet air to 30 °C.
!The GPU list is a single card, the 72 W NVIDIA L4 — a Controlled part sold only on the “for AI” base models. Four of them need specific Gen5 risers in slots 1, 3, 4 and 5, Performance fans and no more than 30 °C ambient.
!Power capping is not supported, either through XCC2 Platinum or XClarity Energy Manager, and memory mirroring and rank sparing are not available.
Processors45 SKUs
Cores / CPU8–160
DIMM slots12
Backplanes17
Max bays16
GPUsup to 5
PSU options8 · to 1,800 W
02 — Processors
45 supported processors, mapped
Lenovo lists 45 processors: 25 5th Gen EPYC 9005 (“Turin”) models, four of them Zen 5c, plus 20 4th Gen EPYC 9004 models that include the Zen 4c “Bergamo” 9734 and 9754. Core counts run from 8 (9015) to 160 (9845) and TDP from 125 W to 400 W, and the SR635 V3 accepts exactly one of any of them. The chart plots cores against TDP; the explorer beneath it filters the full list.
Processor landscape — cores × TDP
45 SKUs · 2 families
AMD EPYC 9005 25AMD EPYC 9004 20Bubble 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 9654
96 / 192
2.4 GHz
384 MB
360 W
3.8
DDR5-4800
AMD EPYC 9654P
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 9554P
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 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 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 eight P-suffix models (9354P, 9454P, 9554P, 9654P, 9355P, 9455P, 9555P and 9655P) show the same cores, clocks, L3 cache and TDP in Lenovo’s tables as the non-P model of the same number.
5th Gen parts run memory at 6400 MHz only with the DIMMs Lenovo marks as 6400 MHz-capable and current system firmware; other DIMMs run the bus at 6000 MHz. Every 4th Gen part has a 4800 MHz memory bus.
The 9175F and 9575F boost to 5 GHz, and the 16-core 9175F carries 512 MB of L3 cache.
Lenovo’s fan rules allow Standard fans only when the processor is below 240 W and the build has the 10-bay 2.5-inch chassis, no rear drives, no GPUs and no 100GbE-class networking; anything else takes Performance fans. Open-loop Neptune Core builds are the exception, where Lenovo says Standard fans can be configured in most cases.
Platform Secure Boot is enabled by default and binds the processor to the server’s firmware signing key on first power-on. Factory orders can ship with it disabled (feature C18D), but once switched on it cannot be turned off.
03 — Memory
12 DDR5 DIMM slots
The processor provides 12 DDR5 channels and each holds one DIMM, so the 12 slots are the whole memory system: there is no second socket to populate and no two-DIMM-per-channel mode. Lenovo permits 1, 2 or 4 DIMMs, or any even count from 6 to 12; for best performance Lenovo advises a full set of twelve identical part numbers.
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
6400 MHz-rated DIMMs are 5th Gen-only and 4800 MHz-rated DIMMs 4th Gen-only, so the processor generation decides the memory list. The 4th Gen memory table stops at 128 GB, which is 1.5 TB across 12 slots (12 × 128 GB); the 3 TB ceiling needs a 5th Gen processor and 256 GB 3DS RDIMMs.
Mixing rules are strict: no 9x4 with 10x4 DIMMs, no x4 with x8, a single DRAM density (16, 24 or 32 Gb), no 128 GB with 256 GB 3DS parts, and no more than two capacities across the channels.
SDDC (Chipkill) needs x4 DIMMs and is unavailable with 9x4 RDIMMs; memory mirroring and rank sparing are not supported at all.
If a GPU or another hot component is added later, every empty DIMM slot needs a filler; factory builds have the fillers derived automatically.
04 — Storage
17 backplane options, up to 16 bays
Drives live in two zones only, front and rear, and there is no 3.5-inch option. The front takes up to ten 2.5-inch bays or sixteen E1.S EDSFF bays. At the rear, two 2.5-inch bays can be added only alongside a 2.5-inch front, while the alternative pair of 7mm drives sits in slot 3. Each headline layout below is a full front-plus-rear combination taken from Lenovo’s configuration matrix, and the chart that follows maps the individual backplane kits.
Headline layouts
front panel view
Front panel
Rear module
Configs 20 and 35: a 10-bay NVMe backplane, Gen4 (BCQQ) or Gen5 (BRQX), plus the 2-bay Gen4 NVMe rear backplane (BDY6). All twelve drives connect to onboard NVMe ports, M.2 boot is supported and 7mm drives are not.
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
RAID 540-8i for M.2/7mm NVMe Boot Enablement — RAID. CTO feature (max 1): RAID 540-8i operating in Tri-Mode, installed in PCIe slot 1 or 2, required for RAID-1 on NVMe drives in the M.2 SATA/x4 NVMe 2-Bay Adapter (4Y37A79663) or the 7mm SATA/NVMe 2-Bay Rear Enablement Kit v2 (BU0N); dedicated to M.2/7mm boot drives and cannot be used with other drive bays; M.2 RAID and 7mm RAID are mutually exclusive
RAID 940-16i 4GB Flash PCIe Gen4 12Gb Adapter for U.3 — RAID, 4GB cache. Tri-Mode (U.3 NVMe) variant; DEPRECATED - for existing orders only and being phased out; for new CTO orders use the standard 940 adapter (B8NY, B8NW, BM35, B8NZ or B8P0) plus Tri-Mode Enablement feature CH5Z (U.3 drives, AnyBay backplane); RAID levels: 0, 1, 10, 5, 50, 6, 60
RAID 940-16i 8GB Flash PCIe Gen4 12Gb Adapter for U.3 — RAID, 8GB cache. Tri-Mode (U.3 NVMe) variant; DEPRECATED - for existing orders only and being phased out; for new CTO orders use the standard 940 adapter (B8NY, B8NW, BM35, B8NZ or B8P0) plus Tri-Mode Enablement feature CH5Z (U.3 drives, AnyBay backplane); RAID levels: 0, 1, 10, 5, 50, 6, 60
RAID 940-8i 4GB Flash PCIe Gen4 12Gb Adapter for U.3 — RAID, 4GB cache. Tri-Mode (U.3 NVMe) variant; DEPRECATED - for existing orders only and being phased out; for new CTO orders use the standard 940 adapter (B8NY, B8NW, BM35, B8NZ or B8P0) plus Tri-Mode Enablement feature CH5Z (U.3 drives, AnyBay backplane); RAID levels: 0, 1, 10, 5, 50, 6, 60
RAID 940-8i 8GB Flash PCIe Gen4 12Gb Adapter for U.3 — RAID, 8GB cache. Tri-Mode (U.3 NVMe) variant; DEPRECATED - for existing orders only and being phased out; for new CTO orders use the standard 940 adapter (B8NY, B8NW, BM35, B8NZ or B8P0) plus Tri-Mode Enablement feature CH5Z (U.3 drives, AnyBay backplane); RAID levels: 0, 1, 10, 5, 50, 6, 60
ThinkSystem 440-16e SAS/SATA PCIe Gen4 12Gb HBA — HBA. External SAS HBA (JBOD to external enclosures/tape), part 4Y37A09724 feature B8P7 - lp1609 L2961
Onboard controllers are JBOD only: SATA for up to 12 drives and NVMe for up to 16, each NVMe drive on its own x4 link at up to PCIe Gen5 depending on backplane and drive.
Tri-Mode lets a RAID 940-8i or 940-16i drive U.3 NVMe alongside SAS and SATA on an AnyBay backplane, with each NVMe drive on one PCIe lane. Since July 2026 Lenovo configures it as a standard 940 adapter plus feature CH5Z, and is retiring the older “for U.3” adapter codes.
With PCIe RAID adapters the server holds two flash-backed supercaps (three when an internal CFF adapter is fitted), which limits how many RAID 940 cards it can take.
Boot is an internal M.2 adapter or two rear 7mm drives in slot 3. M.2 RAID and 7mm RAID cannot be combined, and a RAID 540-8i used for M.2 or 7mm NVMe RAID cannot serve any other bays.
A front backplane cannot be upgraded in place to a larger one — the existing one has to come out first — and front backplane kits are sold without cables.
Every documented backplane
14 with drive bays
2.5-inch3.5-inchEDSFF (E1.S / E3.S)
05 — Accelerators & I/O
GPUs, PCIe and networking
Lenovo’s GPU table for this server has one entry: NVIDIA’s L4 24 GB, a passive single-width card rated at 72 W and classed as Controlled, which restricts ordering to the “for AI” base models. Up to four fit, one each in slots 1, 3, 4 and 5, which uses both front slots and specific Gen5 risers. Any GPU build excludes rear drives and flash storage adapters, needs Performance fans and is limited to 30 °C ambient. Up to 4 × NVIDIA L4 (72 W) in slots 1, 3, 4 and 5; Lenovo’s summary table quotes 5 single-wide GPUs.
NVIDIA L4 24GB PCIe Gen4 Passive GPU
single-wide
24GB · up to 4
I/O topology
128 lanes per CPU
The server takes one processor, so all 12 memory channels and every PCIe lane come from that single EPYC. Lenovo rates each supported EPYC at 128 PCIe 5.0 lanes but says only half, 64, are usable for slots and NVMe drives.
The rear riser choice sets the slots: three low-profile x16, one low-profile plus one full-height, one slot plus two rear 2.5-inch bays, or two slots plus two 7mm drives. No more than two rear slots can run at Gen5.
Front slots need the 4 × 2.5-inch Front I/O chassis (feature BQ7M). The OCP slot then moves to the front and the rear OCP position is disconnected, and neither the closed-loop heatsink nor the security bezel can be used.
In 2.5-inch builds a CFF RAID adapter or HBA sits in its own internal bay, cabled to an onboard NVMe port, so no PCIe slot is used.
Only one OCP adapter can be fitted, and the optional redundant XCC2 management port takes the rear OCP slot instead of a network card.
The NVIDIA ConnectX-8 400GbE adapter requires a 5th Gen processor and a riser without retimers.
06 — Power & cooling
8 power supplies, 750–1,800 W
Lenovo offers eight hot-swap supply options: Titanium AC at 750 W (in two versions), 1100 W and 1800 W; Platinum AC at 750 W, 1100 W and 1800 W; and a single 1100 W unit fed from −48 V DC. The chassis has room for two, and a redundant pair must match exactly.
AC−48 V DC
Table 68 ticks 110 V AC only for the two Platinum units rated 750 W and 1100 W and shows every other AC supply as 220 V-only, even though the note printed under it describes all supported supplies as auto-ranging; this page follows the table. Running the 1100 W unit on low-line power calls for a cable rated above 10 A.
AC units all use a C14 inlet. The DC unit connects through a Weidmuller TOP 4GS/3 7.6 terminal and is specified for a −48 to −60 V input at 26 A inlet current.
1800 W supplies add depth: their handles reach 782 mm behind the rack-flange mating surface, against 754 mm with 1100 W and smaller units.
Lenovo quotes heat output of 837 W (2859 BTU/hr) for a minimum configuration and 2393 W (8164 BTU/hr) for a maximum one.
Five to seven 40 mm dual-rotor hot-swap fans give N+1 rotor redundancy, with another fan in each supply. Seven are needed with front slots, or with EDSFF bays plus an OCP card, GPU or slot-1 adapter.
In China, all supplies also accept 240 V DC.
07 — Management, security & OS
Run it, secure it, choose the OS
Management
XClarity Controller 2 (XCC2) on an ASPEED AST2600 BMC (dual-core ARM Cortex A7, 1.2 GHz)
XCC2 Platinum licence: remote console, virtual media mounting, System Guard, Enterprise Strict Security mode (CNSA 1.0), Neighbor Group
Rear 1GbE RJ45 management port · optional ThinkSystem V3 Management NIC Adapter Kit in the OCP slot
XClarity Provisioning Manager (UEFI, F1 at boot)
XClarity One cloud management, licensed per endpoint (Starter tier up to 10 devices)
XClarity Essentials: OneCLI, UpdateXpress, Bootable Media Creator
XClarity Energy Manager (one node licence included with Platinum) · Lenovo Capacity Planner
IPMI 2.0 (IPMI-over-LAN off by default), SNMPv3, Redfish, CIM-XML
Optional pull-out Integrated Diagnostics Panel (8 × 2.5-inch or EDSFF fronts, CTO only) or External Diagnostics Handset
XClarity One Mobile over the front USB management port
Security
Platform Firmware Resiliency hardware Root of Trust (NIST SP 800-193)
Integrated TPM 2.0 · Nationz TPM 2.0 for China (CTO only)
AMD Platform Secure Boot (on by default; permanent once enabled)
UEFI Secure Boot enabled in the factory or later by the customer
AMD SEV, SEV-ES, SEV-SNP and TSME memory encryption
System Guard component-change monitoring (XCC2 Platinum)
Self-encrypting drives with KMIP key managers (IBM SKLM, Thales KeySecure)
NIST SP 800-147B compliant · FIPS 140-3 (in progress) and CNSA Suite 1.0 cryptography for XCC
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)
Red Hat Enterprise Linux 8, 9 and 10
SUSE Linux Enterprise Server 15 and 16
Ubuntu 22.04, 24.04 and 26.04 LTS (20.04 with 4th Gen EPYC)
VMware ESXi 8.0 U3, 9.0 and 9.1 (7.0 U3 onward with 4th Gen) · factory preload, not with NVIDIA GPUs
08 — Compare
SR635 → SR635 V3
Lenovo’s comparison table sets the SR635 V3 against the original SR635. That table describes the V3 at its 4th Gen launch specification (128 cores, 360 W); the V3 column here uses the current guide’s own figures, which include 5th Gen EPYC.
Previous generationThinkSystem SR635
This modelThinkSystem SR635 V3
Processor
1 × 2nd or 3rd Gen EPYC · up to 64 cores · 280 W
1 × 4th or 5th Gen EPYC · up to 160 cores · 400 W
PCIe lanes per CPU
128 × PCIe 4.0
128 × PCIe 5.0
Memory
DDR4 to 2933 MHz · 8 channels · 16 DIMMs (2 DPC)
DDR5 to 6400 MHz · 12 channels · 12 DIMMs (1 DPC)
Maximum memory
2 TB (16 × 128 GB)
3 TB (12 × 256 GB)
Front drive bays
4 × 3.5" or 10 × 2.5"
10 × 2.5" or 16 × E1.S · no 3.5"
Mid-chassis bays
4 × 2.5" NVMe
None
Rear drive bays
2 × 2.5" SAS/SATA or NVMe
2 × 2.5" or 2 × 7mm
PCIe slots
Up to 3, all rear, all Gen4
Up to 5 (3 rear, 2 front), Gen4/Gen5 mix
OCP 3.0
Rear only, PCIe Gen4
Rear or front, PCIe x16
GPUs
Up to 3 × 75 W
Up to 4 × 75 W
Management
ASPEED 2500 BMC · limited XClarity
XClarity Controller 2 · PFR Root of Trust
AC power supplies
500, 750 and 1100 W
750, 1100 and 1800 W
Source: Lenovo Press LP1609 (SR635 V3 product guide), Table 2 — Comparing the SR635 V3 to the SR635; V3 processor and memory figures from Tables 3, 13–16 and 21 of the same guide.
The SR635 V3 family side by side
The SR635 V3 has three AMD EPYC 9004/9005 siblings in the V3 generation: the 1U two-socket SR645 V3, the 2U single-socket SR655 V3 and the 2U two-socket SR665 V3. Intel buyers have the SR630 V3 (Xeon Scalable) and SR630 V4 (Xeon 6) in the same 1U format. Every bar in the family matrix is drawn from that server’s verified spec file.
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.
Four example specifications for a one-socket, one-rack-unit server, built solely from parts our configurator offers for the SR635 V3. Any of them can be opened and edited; before quoting, we run the specific combination past Lenovo’s thermal, riser and fan rules.
Virtualisation
Single-socket hypervisor host
Where software is licensed per socket, one 48-core EPYC 9455P covers a whole node: twelve 128 GB DIMMs, one per channel, give 1.5 TB, six NVMe drives on the onboard ports hold a local datastore, and two M.2 drives boot the hypervisor. At 300 W the processor stays below the 320 W point where Lenovo’s cooling restrictions start.
1 × AMD EPYC 9455P — 48 cores @ 3.15 GHz, 300 W
12 × 128 GB TruDDR5 6400 MHz — 1.5 TB, one DIMM per channel
The onboard NVMe ports provide no RAID. To mirror the M.2 pair, choose an M.2 adapter with integrated RAID or add the RAID 540-8i boot-enablement feature.
The EPYC 9175F gives just 16 cores a 4.2 GHz base, a 5 GHz boost and 512 MB of L3 cache, which suits transaction databases where software is licensed per core rather than bought for core count. Ten NVMe drives run straight from the onboard ports.
1 × AMD EPYC 9175F — 16 cores @ 4.2 GHz, 320 W
12 × 64 GB TruDDR5 6400 MHz — 768 GB
10 × 3.84 TB NVMe U.3 on a 10-bay NVMe backplane
Broadcom 57414 2 × 25GbE OCP 3.0
2 × 1100 W Titanium
Windows Server 2025
At 320 W the 9175F keeps all ten front bays only with Lenovo’s Neptune Liquid to Air closed-loop heatsink, ordered with the 25 °C data-centre environment option, or with the open-loop Neptune Core module. The closed-loop module needs Gen4 rather than Gen5 NVMe on a 10-bay NVMe front and excludes M.2, rear 2.5-inch drives, 256 GB DIMMs and CFF adapters, so this build boots from the front drives; NVMe drives with a 320–400 W processor also hold ambient to 35 °C.
Ten front and two rear NVMe bays give twelve drives, each on its own x4 link from the processor with no RAID card or NVMe adapter in between, for scale-out storage software that handles redundancy itself. A 64-core, 300 W EPYC 9535 leaves compute headroom, and a 100GbE OCP card carries replication traffic.
1 × AMD EPYC 9535 — 64 cores @ 2.4 GHz, 300 W
12 × 64 GB TruDDR5 6400 MHz — 768 GB
12 × 7.68 TB NVMe U.3 — 10 front + 2 rear, 92.16 TB raw
2 × 480 GB M.2 NVMe boot
Broadcom 57508 2 × 100GbE OCP 3.0
2 × 1100 W Titanium
Red Hat Enterprise Linux 9
Rear 2.5-inch bays leave only PCIe slot 1, rule out GPUs and 7mm drives, and limit inlet air to 30 °C. Stay below 320 W: neither the closed-loop heatsink nor the open-loop Neptune Core module can be combined with rear 2.5-inch drives.
Four NVIDIA L4 cards (24 GB, 72 W each), the maximum in Lenovo’s GPU table, bring inference acceleration to a 1U server. A 32-core, 210 W EPYC 9335 feeds them, and four front NVMe bays hold models and data, because this layout has no M.2 or rear drives.
1 × AMD EPYC 9335 — 32 cores @ 3 GHz, 210 W
4 × NVIDIA L4 24 GB, single-width, 72 W
12 × 64 GB TruDDR5 6400 MHz — 768 GB
4 × 7.68 TB NVMe U.3 in a 4-bay front
Intel E810-DA2 2 × 25GbE OCP 3.0 (front position)
2 × 1800 W Titanium
Ubuntu Server 24.04 LTS
Because the L4 is Controlled, Lenovo supplies it only in “for AI” base models. Four cards need specific Gen5 risers in rear slots 1 and 3 and front slots 4 and 5, so the build uses the 4-bay Front I/O chassis, which supports no M.2; 7mm drives are also out, as they occupy slot 3 and exclude GPUs. GPU builds exclude rear drives, need Performance fans and are limited to 30 °C ambient, and Lenovo’s factory ESXi preload is not offered with NVIDIA GPUs.
No Lenovo models sit in our refurbished configurator; the closest re-certified stand-ins come from Dell and HPE — 1U, one-socket AMD EPYC servers of the DDR4 era. Each gives up DDR5 and PCIe 5.0 but keeps the one-processor, one-rack-unit shape.
Gen10 Plus · re-certified
HPE ProLiant DL325 Gen10 Plus
1U · one socket
1 × EPYC 7002/7003 · up to 64 cores
16 DIMM slots · up to 4 TB DDR4
10 × SFF / NVMe · 128 PCIe 4.0 lanes · iLO 5
The nearest like-for-like: a single Rome or Milan processor with up to 64 cores and PCIe 4.0 lanes, for consolidation where DDR4 capacity is enough.
1 or 3 years by machine type · CRU and onsite, 9 × 5 next business day
12 — FAQ
SR635 V3 questions, answered from the documentation
What is the maximum memory of the Lenovo ThinkSystem SR635 V3?
Twelve 256 GB 3DS RDIMMs give 3 TB, since the single EPYC has 12 channels and each carries one DIMM. The 256 GB part appears only in Lenovo’s 5th Gen memory table; with a 4th Gen EPYC the largest listed DIMM is 128 GB, which gives 1.5 TB across the 12 slots.
Which processors does the SR635 V3 support?
A single AMD EPYC chosen from 45 listed SKUs: 25 5th Gen 9005 models spanning the 8-core 9015 to the 160-core 9845, and 20 4th Gen 9004 models topping out at the 128-core 9754. TDPs run from 125 W to 400 W, and parts of 320 W or more bring cooling or drive-bay restrictions.
How many drives does the SR635 V3 hold?
Up to twelve 2.5-inch drives, ten at the front and two at the rear, or sixteen E1.S EDSFF NVMe drives at the front. There are no 3.5-inch bays. For boot, an internal M.2 module holds one or two drives, or a pair of 7mm drives sits at the rear.
Can the SR635 V3 take GPUs?
Yes: up to four NVIDIA L4 24 GB cards at 72 W each, the only GPU in Lenovo’s GPU table, although its summary specification quotes five single-wide GPUs. The L4 is a Controlled GPU sold only on the “for AI” base models, and GPU builds rule out rear drives and cap ambient temperature at 30 °C.
How many PCIe slots does the SR635 V3 have?
Up to five plus one OCP 3.0 slot: three at the rear on two risers and two at the front. The front slots require the four-bay Front I/O chassis and move the OCP slot to the front. At most two rear slots can be PCIe 5.0.
What power supplies does the SR635 V3 use?
Two matching hot-swap units, picked from AC models of 750, 1100 or 1800 W in 80 PLUS Titanium or Platinum grades, plus one 1100 W supply that runs on −48 V DC. In Lenovo’s supply table only the 750 W and 1100 W Platinum models are marked for 110 V input, though a note under it calls every unit dual-voltage.
Should I choose the SR635 V3 or the two-socket SR645 V3?
Both are 1U EPYC 9004/9005 servers with up to 12 × 2.5-inch or 16 E1.S bays. The SR645 V3 takes one or two processors, 24 DIMM slots and up to 6 TB, and adds a 4 × 3.5-inch front option; fitted with one processor it has 12 DIMMs and loses slot 3. If one processor is the plan, the SR635 V3 is designed around it; the SR645 V3 suits builds that may need a second processor or more memory.
How does the SR635 V3 compare with the 2U SR655 V3?
The SR655 V3 has the same single EPYC processor and 12-DIMM, 3 TB memory design, but its 2U chassis holds up to 40 × 2.5-inch or 20 × 3.5-inch drives, up to 10 PCIe slots and up to three double-wide or eight single-width GPUs. The SR635 V3 makes sense when rack density matters more than drive count or GPU capacity.
What changed from the original SR635?
Lenovo’s comparison table shows memory moving from DDR4 with 8 channels and 16 DIMMs (2 TB) to DDR5 with 12 channels of one DIMM each (3 TB), PCIe moving from Gen4 to Gen5, and slots growing from three rear to up to five. The V3 drops 3.5-inch and mid-chassis bays, adds 16 × E1.S and 7mm boot options, and replaces the ASPEED 2500 BMC with XClarity Controller 2.
Is the Lenovo ThinkSystem SR635 V3 end of life?
Lenovo’s product guide still lists current processors and options for the SR635 V3, including changes marked as new in July 2026, and it gives no model-wide end-of-service date. Cover for an individual unit runs with its warranty or Lenovo service agreement, and the end-of-life checker linked below lists any dates Lenovo announces.
Sources & verification
Where these figures come from
Lenovo ThinkSystem SR635 V3 Server Product Guide (publication date is not printed in the text export; guide contains ‘New as of July 2026’ notes) — Key features, SR635 V3 vs SR635 (Table 2), standard specifications (Table 3), processor Tables 13–16 and thermal rules, memory Tables 21–22 and rules, backplanes and storage configurations (Tables 25–30), M.2 (Table 37), storage adapters (Table 42), riser and front-slot Tables 57–59, OCP and GPU Tables 62 and 66, fans (Table 67), power supplies (Table 68), systems management, security, OS support, dimensions (Table 86), operating environment and warranty.
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.
