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Lenovo ThinkSystem, generation by generation.

ThinkSystem is the line Lenovo built out of the IBM System x business, and its naming is the most literal of the four server lines on this site. SR is a rack server, ST a tower, SD a dense node, DE and DM the storage arrays. The first digit of the number is the socket class and the rest is the position in the range: SR250 is single-socket entry, SR630 the 1U two-socket, SR650 the 2U two-socket, SR850 and SR950 the four- and eight-socket machines.

86models listed
31refurbished
3generations compared

Generations are a suffix rather than a new number. SR650, SR650 V2, SR650 V3 and SR650 V4 are the same 2U server four times over, which makes the version suffix the single most important thing to read in a listing — and the easiest to skim past.

The storage side of the line uses different letters for a real reason. DE arrays are the block-storage family and DM the unified family; they are not versions of each other and one does not replace the other.

SR650, the 2U two-socket, across versions

3 steps

Figures come from the specification sheets of the SR650 units we list. The V2 step is deliberately not described below — see the note under the table.

V1

SR650

Processor
2 sockets, 1st/2nd Gen Intel Xeon Scalable, up to 28 cores, up to 205 W
Memory
24 TruDDR4 slots, 2666/2933 MT/s, up to 3 TB RDIMM (6 TB with persistent memory)
Storage & I/O
Up to 24 SFF SAS/SATA/NVMe or 12 LFF, plus rear bays; RAID 530/730/930/940 series; VROC for NVMe

What changed. The first ThinkSystem 2U — the platform the rest of the line is measured against.

What it means. Plentiful, inexpensive and entirely adequate as a virtualisation host or a file server. Its ceiling is 24 DIMM slots and a DDR4 bus; if you are not near either, the newer versions buy you nothing you will notice. We list this version refurbished only — a first-version SR650 has not been current for some time.

Figures above are from the specification sheet of:
V3

SR650 V3

Processor
2 sockets, 5th Gen Intel Xeon Scalable up to 64 cores at 385 W, or 4th Gen up to 60 cores at 350 W
Memory
32 TruDDR5 slots, up to 5600 MT/s, up to 8 TB (12 TB with persistent memory)
Storage & I/O
Up to 40 x 2.5-inch total across front, mid and rear, up to 36 NVMe; or 12 LFF front with mid and rear; up to 12 PCIe slots plus OCP 3.0

What changed. DDR4 to DDR5, 24 DIMM slots to 32, and a drive count that more than doubles once mid and rear bays are counted.

What it means. The version to pick when density is the point — the drive and PCIe counts here are unusually high for a 2U, which is what makes it a good all-flash or GPU host.

Figures above are from the specification sheets of:
V4

SR650 V4

Processor
2 sockets, Intel Xeon 6700/6500 series, up to 86 cores, up to 350 W
Memory
32 DDR5 slots, up to 8 TB, 6400 MT/s (MRDIMM up to 8000)
Storage & I/O
Up to 40 x 2.5-inch (36 NVMe), or 16 LFF, or 32 E3.S; up to 10 PCIe Gen5 slots plus 2 OCP 3.0

What changed. Xeon 6, MRDIMM support, and E3.S alongside 2.5-inch bays.

What it means. The current machine. The memory story is the interesting one here: MRDIMM raises bandwidth without raising slot count, which matters for in-memory workloads more than the core count does.

Figures above are from the specification sheet of:

The V2 generation sits between V1 and V3 and is not described above on purpose: the specification sheet we hold against our V2 record does not match what a V2 is, so there is nothing here we would stand behind. We can source and quote V2 units — ask, and the quote will carry the sheet for the exact machine.

Which one for which job

1U instead of 2U

SR630 of the matching version. Same platform, same generation, half the height — fewer drive bays and fewer slots, which is the trade you are making for rack space.

A single-socket or entry machine

SR250 V3 in the rack, ST250 V3 or ST50 V3 as a tower. These take the same management stack as the larger machines, so a small site does not become a second standard to administer.

Four sockets and up

SR850 for four, SR950 for eight. Same reasoning as anywhere else in this catalogue: they exist for software licensed per machine, and for memory footprints a two-socket box cannot reach.

Storage rather than compute

DE arrays for block storage, DM for unified. They are separate families rather than steps in one range, so the question is which protocol set you need, not which is newer.

Lenovo ThinkSystem models we list

86 models

Rack Servers57

NAS & Storage19

Tower Servers10

Questions we get about Lenovo ThinkSystem

More than the model number does. An SR650 and an SR650 V3 differ by a socket generation, a memory generation, eight DIMM slots and roughly double the drive capacity. When you compare two listings, compare the suffixes first — the price gap between them is usually explaining exactly that.

It is the continuation of that business, which Lenovo acquired, but ThinkSystem is a Lenovo-designed line rather than a rebadge. System x models such as the x3650 are a separate, older family — we list what we hold of those as end-of-sale rather than as current stock.

SR635 and SR645 are single- and dual-socket EPYC machines in the same chassis family. Drives, caddies and the management stack carry across; the board, the memory channel layout and the core economics do not. Worth pricing against the Intel equivalent when you are buying cores rather than clock.

Enterprise hardware reprices daily, and no two builds of the same model cost the same — memory, drives and the controller move the number more than the chassis does. A sticker would be wrong by the time you read it. Send the model and the configuration and you get today's rate, usually inside a business day, held in the contract.

A Lenovo ThinkSystem model that is not listed here?The catalogue shows what we hold, not the limit of what we source. Send the model, the generation or a full parts list and you get a price and a lead time inside 48 hours.

Send the model

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Every model · new & refurbished

Same 1-yr warranty, same QC