Lenovo SR650 V4 vs Lenovo SR650a V4
A specification-by-specification comparison of the Lenovo ThinkSystem SR650 V4 and the Lenovo ThinkSystem SR650a V4, built from Lenovo’s own documents. 2 headline measures favour the SR650 V4 and none favour the SR650a V4, and 27 processors appear in both lists.
Bottom line. SR650 V4 leads on storage density, AI and acceleration. Neither vendor publishes benchmarks for these machines, so every call here is made on what their documents state.
The measures that decide it
Each row is a figure both vendors publish. Bars show the split between the two; a badge marks the larger figure, which is not always the better buy — a shallower chassis or a lower power ceiling can matter more.
Which one, and why
Drawn from the measures above and each model’s own data sheet. Neither vendor publishes benchmark results for these servers, so nothing here claims one is “faster”.
Choose the SR650 V4 if…
- Drive bays: 40 against 8 on the SR650a V4
- Accelerators: Up to 10 against Up to 8 on the SR650a V4
- Up to 36 NVMe drives — 24 front, 8 mid and 4 rear — connect straight to the processors on a full x4 link each, so an all-flash build needs no retimer adapters.
Choose the SR650a V4 if…
- One 2U chassis spans eight low-profile L4 cards, four double-wide cards of up to 450 W, or a pair of 600 W H200 NVL or RTX PRO 6000 Blackwell GPUs, all in PCIe 5.0 front slots.
Where each one pulls ahead
Calls made on documented capacity only — cores, memory, bays, accelerators and network options — with the figures behind each one shown.
Side by side, differences first
Everything both documents state, grouped. The default view hides rows where the two machines are identical.
Memory
| Specification | SR650 V4 | SR650a V4 |
|---|---|---|
| Fastest rated speed | 8,000 MT/s | 8,800 MT/s |
| Memory types | RDIMM DDR5-6400 · 3DS RDIMM DDR5-6400 · MRDIMM DDR5-8000 (8800 rated) · CXL 2.0 E3.S 2T memory modules | RDIMM DDR5-6400 · 3DS RDIMM DDR5-6400 · MRDIMM DDR5-8800 (operates at 8000) |
Storage
Bay counts are the maximum each document states, including rear and mid-chassis positions.
| Specification | SR650 V4 | SR650a V4 |
|---|---|---|
| Maximum bays | 40 | 8 |
| Documented layouts | 16 | 4 |
| Bay sizes | 3.5-inch · 2.5-inch · E3.S | 2.5-inch · E3.S |
| Boot devices | Internal M.2 RAID B550i-2i SATA/NVMe Enablement Kit (2 x M.2 NVMe, integrated Broadcom RAID) · Internal M.2 RAID B545i-2i SATA/NVMe Adapter (2 x M.2 SATA/NVMe, integrated Broadcom RAID) · Internal M.2 B350i-2i NVMe Enablement Kit (2 x M.2 NVMe x2, VROC RAID) + 4 more | ThinkSystem M.2 RAID B550i-2i SATA/NVMe Enablement Kit (internal, 2x M.2 NVMe, integrated Broadcom RAID) · ThinkSystem M.2 RAID B545i-2i SATA/NVMe Adapter (internal, 2x M.2 SATA/NVMe, integrated Broadcom RAID) · ThinkSystem M.2 B350i-2i NVMe Enablement Kit (internal, 2x M.2 NVMe x2, VROC RAID) + 4 more |
| Storage controllers | 24 | 23 |
Accelerators & I/O
| Specification | SR650 V4 | SR650a V4 |
|---|---|---|
| Accelerators supported | Up to 10 | Up to 8 |
| Double-wide cards listed | 2 | 4 |
| PCIe network slots | 10 | 14 |
Power & platform
| Specification | SR650 V4 | SR650a V4 |
|---|---|---|
| Chassis depthVendors measure depth differently — see each data sheet | 796 mm | 924 mm (36.4 in.) |
Processors, memory, bays and power
The same charts each data sheet carries, drawn to the same scale so the two ranges can be read against each other.
SR650 V4: processors by cores and TDP
SR650a V4: processors by cores and TDP
SR650 V4: memory with every slot filled
SR650a V4: memory with every slot filled
SR650 V4: drive bays
Front panel
12 × 3.5" SAS/SATA at the front — 12 bays in total.
SR650a V4: drive bays
Front panel
8 × 2.5" NVMe at the front — 8 bays in total.
SR650 V4: power supplies
SR650a V4: power supplies
27 processors you can order in either
Both vendor documents list these parts, so a build can be matched across the two and the comparison comes down to the chassis: 0 more are exclusive to the SR650 V4 and 0 to the SR650a V4.
| Processor | Cores | TDP |
|---|---|---|
| Intel Xeon 6 6787P | 86 | 350 W |
| Intel Xeon 6 6781P | 80 | 350 W |
| Intel Xeon 6 6760P | 64 | 330 W |
| Intel Xeon 6 6761P | 64 | 350 W |
| Intel Xeon 6 6767P | 64 | 350 W |
| Intel Xeon 6 6740P | 48 | 270 W |
| Intel Xeon 6 6741P | 48 | 300 W |
| Intel Xeon 6 6747P | 48 | 330 W |
| Intel Xeon 6 6736P | 36 | 205 W |
| Intel Xeon 6 6530P | 32 | 225 W |
| Intel Xeon 6 6730P | 32 | 250 W |
| Intel Xeon 6 6731P | 32 | 245 W |
SR650 V4 vs SR650a V4, answered
Is the SR650 V4 or the SR650a V4 the faster server?
Neither document publishes benchmark results, so this page compares what they do state. The SR650 V4 lists 27 processors up to 86 cores at 350 W; the SR650a V4 lists 27 up to 86 cores at 350 W. Fully populated that is 172 cores against 172.
Which holds more memory?
The SR650 V4 has 32 DIMM slots and a stated ceiling of 8 TB. The SR650a V4 has 32 and 8 TB.
Which takes more drives?
SR650 V4: 40 bays across 16 documented layouts. SR650a V4: 8 across 4. Counts include rear and mid-chassis positions where the vendor documents them.
Can either take GPUs?
SR650 V4: up to 10 accelerators, 2 double-wide cards listed. SR650a V4: up to 8, 4 double-wide listed.
Do they share any processors?
Yes — 27 processors appear in both documents, including the Intel Xeon 6 6787P. That makes a like-for-like build possible on either server.
Where these figures come from. SR650 V4: Lenovo ThinkSystem SR650 V4 Server (September 8, 2026) (Lenovo document). SR650a V4: Lenovo ThinkSystem SR650a V4 and SR650i V4 Servers (August 27, 2026) (Lenovo document). Each claim on this page is derived from those documents, checked page by page on the two data sheets, and carries no pricing.
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