Lenovo ThinkSystem SR (AMD): EPYC-based rack servers
The AMD side of ThinkSystem SR runs 4th/5th generation EPYC across five codes: SR635 and SR645 are 1U (single and dual-socket), SR655 and SR665 are 2U (single and dual-socket, up to 40 drives), and SR675 is a 3U GPU-dense platform taking up to eight double-wide 600 W accelerators with N+N redundant power.
Technical specification
| Model | Form factor | Socket / processor generation | Max memory | Drive bays | GPU support | Power supply | Network |
|---|---|---|---|---|---|---|---|
| SR635 V3 | 1U | 1x 4th/5th Gen AMD EPYC, up to 160 cores | 12x TruDDR5, 1.5 TB max | Up to 12x 2.5″ or 16x EDSFF | Up to 4x single-width | Titanium/Platinum, dual redundant | OCP 3.0 mezz + 1GbE mgmt |
| SR645 V3 | 1U | 2x 4th/5th Gen AMD EPYC, up to 160 cores each | 24x TruDDR5, 6 TB max | Up to 4x 3.5″ / 12x 2.5″ / 16x EDSFF | Up to 4x single-width | Titanium/Platinum, dual redundant | OCP 3.0 mezz |
| SR655 V3 | 2U | 1x 4th/5th Gen AMD EPYC, up to 160 cores | 12x TruDDR5, 1.5 TB max | Up to 20x 3.5″ / 40x 2.5″ | Up to 3x double-width or 8x single-width | Titanium/Platinum, dual redundant | OCP 3.0 mezz |
| SR665 V3 | 2U | 2x 4th/5th Gen AMD EPYC, up to 160 cores each | 24x TruDDR5, 6 TB max | Up to 20x 3.5″ / 40x 2.5″ | Up to 8x single-width LP or 3x double-width | Titanium/Platinum, dual redundant | 1x OCP 3.0 mezzanine |
| SR675 V3 | 3U | 1-2x 4th/5th Gen AMD EPYC per node | 24x DDR5, 6 TB max | Up to 8x 2.5″ or 6x EDSFF E1.S | Up to 8x double-width 600 W GPUs | Up to 4x 2600 W Titanium, N+N redundant | 6x PCIe Gen5 + 1x OCP 3.0 |
Source of the values: Lenovo ThinkSystem SR665 V3 datasheet. All five codes are documented from Lenovo’s own datasheets (SR665 V3 held locally as PDF; SR635/SR645/SR655/SR675 V3 confirmed from lenovopress.lenovo.com). An en dash means the manufacturer does not publish that value in the source we hold; we do not fill it in with an estimate. Confirm every figure against the current manufacturer document before it is written into a contract.
The codes we quote in this family are SR635 V3, SR645 V3, SR655 V3, SR665 V3 and SR675 V3. Send us the workload and the constraints, and we will confirm availability, lead time and the exact configuration.
Which one should you choose?
Single-socket 1U (SR635) and single-socket 2U (SR655) solve different problems
SR635 gives up 12x 2.5-inch drive bays for a compact 1U footprint at up to 160 cores; SR655 keeps the single socket but opens up to 40 drives in 2U for a storage-heavy single-socket role such as software-defined storage where per-socket licensing matters. Pick based on the drive count, not just the U height.
SR645 and SR665 are the dual-socket options at 1U and 2U respectively
Both take up to 160 cores per processor across two sockets; SR645 stays in 1U with a narrower drive count (up to 16x EDSFF or 12x 2.5-inch) while SR665 opens to the same up to 40-drive ceiling as SR655. If drive count matters more than rack density, SR665 is the better dual-socket fit.
SR675’s GPU density needs power planning before it needs a quote
Eight double-wide 600 W GPUs plus one or two EPYC processors is a serious power draw, and SR675 V3 answers with up to four 2600 W Titanium PSUs in N+N redundancy. Confirm the room’s power feed can support this before the configuration goes into a proposal; this is not a drop-in replacement for a standard 2U server slot.
All five codes support NVIDIA’s current data-centre accelerator range
SR675 V3 specifically lists support for NVIDIA Blackwell, Hopper, Lovelace and Ampere accelerators alongside AMD Instinct MI series; a wide compatibility range that reduces the risk of choosing a chassis that cannot take next year’s GPU generation. Confirm the specific accelerator SKU’s power draw against the chassis PSU configuration.
Where it fits, and where it does not
Fits AMD-based virtualization, software-defined storage or GPU-dense acceleration across a matched set of 1U, 2U and 3U chassis under one Lenovo XClarity management layer. Does not fit a site standardised on Intel; see the SR (Intel) page.
What we need in order to quote it
- Single or dual socket, and 1U or 2U rack space
- Drive count needed, since it varies significantly across the five codes
- Whether GPU-dense SR675 is required and the room’s power feed for it
- Specific accelerator model if SR675 is chosen
Request a Quote
Tell us the usable capacity, the protocol and the delivery country. A priced quote comes back within 48 hours, usually with a second option so the trade-off is visible.
