Lenovo System x3550 M5: 1U Specs, IBM Parts and Buying

The Lenovo System x3550 M5 is the 1U counterpart to the x3650 M5, and it carries the same IBM-to-Lenovo identity that causes ordering confusion. This covers both the form factor decision and the part numbering.

What is the Lenovo System x3550 M5?

A dual-socket 1U rack server on socket LGA 2011-3, supporting Intel Xeon E5-2600 v3 and v4 processors, with DDR4 memory across 24 DIMM slots and IMM2 remote management.

It is the direct contemporary of the HPE DL360 Gen9 and the Dell PowerEdge R630.

Is the x3550 M5 an IBM or Lenovo server?

Both, and this is the practical problem when ordering parts.

IBM's x86 server business transferred to Lenovo and the System x line went with it. Three consequences.

The same machine appears under both brands in listings and documentation, depending on when the material was written.

Parts carry more than one number. A component may have an IBM FRU number and a Lenovo option number for the same item — searching both is worthwhile when hunting stock. Our part numbers guide covers why one component carries several numbers.

Documentation is split by era, so a search that fails under one brand may succeed under the other.

The habit that solves it: give the number printed on the part itself rather than one from a document. Our x3650 M5 guide covers the same ground for the 2U machine.

x3550 M5 vs x3650 M5: which do I need?

The same 1U against 2U decision as everywhere, and it is decided by drives and cards.

Drive bays. The x3550 M5 takes far fewer, being 1U. If storage capacity lives in the server, the x3650 M5 is the answer.

Expansion slots. Fewer, and low-profile only. Full-height cards do not fit, and a card shipped with only a full-height bracket needs the low-profile one sourced separately — our PCIe guide covers this.

Noise. 1U cools with small fast fans, making it noticeably louder than the 2U machine — not suitable for a room where people work, as our noise guide covers.

Density. Twice the machines per rack, which is the trade you are making.

Also worth knowing: high-power processors are harder to cool in 1U, so check what your specific configuration supports rather than assuming the whole E5-2600 range is available.

x3550 M5 processor and memory support

Intel Xeon E5-2600 v3 and v4 on LGA 2011-3, with the firmware caveat common to this generation: v4 requires firmware support the unit may not have. A v4 processor fits a v3 board and will not post without it, so update before installing rather than after — our E5 v4 guide covers this.

Memory is 24 DIMM slots of DDR4 registered ECC, twelve per processor. A single-processor machine populates twelve only, channels must be filled evenly, and speed can drop as slots fill — our memory guide covers the rules.

For a second processor, the heatsink is a separate 1U-specific part and additional fans are frequently required.

Which RAID controller does the x3550 M5 use?

Commonly a ServeRAID controller, and the check is the same as on any cached controller.

Verify the cache and its backup. Where the battery or capacitor has failed, the controller runs write-through and write performance collapses with no error reported — no failed drive, no array warning, just a slow server. Our controller guide covers this, and it is the first thing to check on any machine that got slow without explanation.

ServeRAID controllers also validate drive firmware, so IBM or Lenovo coded drives are the safe choice on this platform — our OEM guide covers what happens otherwise.

And note that carriers are platform-specific. An HPE Smart Carrier or a Dell carrier will not fit, regardless of the drive inside it.

x3550 M5 vs DL360 Gen9 vs R630: which is the better buy?

An honest comparison, since these three are the realistic alternatives.

Capability is broadly comparable. Same processor generation, same memory architecture, same 1U role.

Parts availability favours HPE and Dell. The DL360 Gen9 and R630 were more widely deployed, so used parts are more plentiful and generally cheaper — which matters on a platform you intend to run for years. Our availability guide covers why installed base size drives spares supply.

The x3550 M5 is frequently cheaper to buy for the same specification, for exactly that reason.

So: buy it where you already run the platform and hold spares and familiarity, or where the price difference justifies a thinner parts market. Starting fresh and wanting the easiest supply position, HPE and Dell are safer — our multi-vendor guide covers why adding a platform multiplies your spares holding rather than adding to it.

Frequently asked questions

Send us the number printed on the part you need and your machine type, and we will match it across both IBM and Lenovo numbering.