ThinkSystem naming decoded

ThinkSystem naming decoded

Lenovo's data-centre server model codes look cryptic, but they are almost entirely systematic. Every current code reads as [letters] + [number] + [optional V-suffix] — for example, SR650 V3. Once you can read the three parts, you can place any Lenovo server in the range without a datasheet. ThinkSystem is Lenovo's server brand introduced in 2017, replacing the older IBM/Lenovo System x line.

The letter prefix — what shape it is

The leading letters tell you the physical form factor:

• SR = Server, Rack — the mainstream rack-mount line (SR630, SR650, SR665, SR850, SR950).
• ST = Server, Tower — pedestal/tower servers for offices and branches (ST50, ST250, ST650).
• SE = Server, Edge — the ruggedised ThinkEdge line for deployment outside a data centre (SE350, SE360, SE450).
• SD = Server, Dense — multi-node/high-density and Neptune liquid-cooled nodes (not covered in this guide).
• SN = Server, Node — the retired Flex-System blade line.

The number — tier and CPU vendor

The first digit after the letters signals the scalability tier:

• 2xx — entry, single-socket (SR250, ST250).
• 5xx — value / essential 2-socket (SR550, SR590).
• 6xx — mainstream / performance 2-socket (SR630, SR650, SR665).
• 8xx — 4-socket scale-up (SR850, SR860).
• 9xx — 8-socket mission-critical (SR950).

The last digit is the quiet but load-bearing one — it encodes the CPU vendor:

• ends in 0 → Intel Xeon (SR630, SR650, SR850, SR950).
• ends in 5 → AMD EPYC (SR635, SR645, SR655, SR665, SR675).

So SR650 V3 is Intel and SR665 V3 is AMD — one digit apart, two completely different platforms (Xeon Scalable + DDR5-5600 vs EPYC + DDR5-6400 with up to 160 cores). Never assume the CPU brand from the family alone; read the last digit.

The V-suffix — which generation

The trailing V2 / V3 / V4 is the generation of that specific model:

• (no suffix) = 1st ThinkSystem generation — Xeon SP Gen 1 (Skylake) / Gen 2 (Cascade Lake), DDR4, PCIe 3.0 (e.g. SR650, SR550, SR860).
• V2 = second iteration — for the mainstream rack line this is 3rd Gen Xeon 'Ice Lake' with DDR4-3200 and PCIe 4.0 (SR630 V2, SR650 V2).
• V3 = third iteration — Intel 4th/5th Gen Xeon (Sapphire/Emerald Rapids) or AMD EPYC Genoa/Turin, DDR5 and PCIe 5.0 (SR630 V3, SR650 V3, SR665 V3).
• V4 = fourth iteration — the newest wave on Intel Xeon 6 / next-gen EPYC (e.g. SR860 V4), DDR5 up to 6400.

Critical caveat for buyers: the V-number is relative to each model, not an absolute silicon generation. One model's V2 and another model's V2 can carry different processors. The clearest example is the edge line — SE360 V2 runs a Xeon D-2700 SoC, nothing like the Ice Lake socket in SR650 V2. Always confirm the actual CPU platform, not just the badge.

From System x to ThinkSystem — reading the legacy codes

The refurb market is still full of the previous System x line, which used a different scheme: x3xxx + M-generation (M4/M5/M6). The M5 generation is the Xeon E5-2600 v3/v4 era (2014–2017). The direct successors map cleanly onto today's rack line:

• x3550 M5 (1U, 2-socket) → succeeded by the SR630 family.
• x3650 M5 (2U, 2-socket) → succeeded by the SR650 family.

Decode table

Code element	Example	What it means
SR	SR650 V3	Rack server
ST	ST650 V3	Tower server
SE	SE450	Edge server (ThinkEdge)
First digit 2	SR250 / ST250	Entry, single-socket
First digit 5	SR550 / SR590	Value 2-socket
First digit 6	SR630 / SR650 / SR665	Mainstream 2-socket
First digit 8	SR850 / SR860	4-socket scale-up
First digit 9	SR950	8-socket mission-critical
Last digit 0	SR650 V3	Intel Xeon inside
Last digit 5	SR665 V3	AMD EPYC inside
No V-suffix	SR650	1st gen (Xeon SP Gen 1/2, DDR4, PCIe 3)
V2	SR650 V2	2nd iteration (rack = Ice Lake, DDR4, PCIe 4)
V3	SR650 V3	3rd iteration (Sapphire/Emerald Rapids or Genoa/Turin, DDR5, PCIe 5)
M5 (System x)	x3650 M5	Legacy pre-ThinkSystem, Xeon E5-2600 v3/v4

Every fact above is drawn from the matching Lenovo Press product guide for each model; see the source list.