M630 vs M640: Blade Generations Compared

Blades are the most infrastructure-shaped servers ever made: the M630 and M640 are not standalone machines but citizens of a chassis — M1000e enclosure or VRTX — that supplies their power, cooling, switching and management. Comparing the two generations therefore means comparing citizens, with the understanding that the city itself is part of every decision.

The shared blade contract

Half-height form factor, two sockets, two SFF bays (boot mirrors more than storage — real data lives on SAN/NAS by design), mezzanine slots feeding chassis I/O modules rather than PCIe cards, and management through the enclosure's CMC in concert with each blade's iDRAC. Sixteen blades per M1000e, sharing six PSUs and nine fans — density economics that made blades the standard for a certain era of corporate virtualization.

Generation versus generation

The familiar 13G-to-14G step, blade edition. M630: E5-2600 v3/v4, 24 DIMM slots of DDR4-2400, iDRAC8 — the same silicon story as the R630, compressed. M640: Xeon Scalable 1st/2nd gen, 16 DIMM slots on six channels at up to 2933 — fewer slots but more bandwidth — iDRAC9, and the ESXi 8 runway that 14G carries everywhere. Mezzanine ecosystems overlap (10/25GbE and FC options per generation), with the M640 reaching newer fabric speeds. Practical ceilings: 22 cores and 768GB-class memory per M630; 28 cores with a leaner slot count per M640 — note that big-memory-per-blade builds actually favor the M630's 24 slots with cheap 32GB sticks.

The real question: should you buy blades at all?

Refurbished blades are extraordinary compute per dollar if the assumptions hold: you have (or want) the enclosure, your storage is external, and one chassis's worth of consolidation fits your world. The enclosure is the commitment — an M1000e is a 10U, three-phase-happy appliance whose switches and firmware form their own project. For labs, that project is the appeal: a complete miniature datacenter, absurdly cheap. For a small business without existing blade infrastructure, two R-series machines deliver the same capacity with none of the ceremony — the honest default.

Buying notes for the committed

Match blade to chassis firmware (M640s need current CMC/midplane revisions in older enclosures — verify before buying blades the chassis cannot seat). Confirm mezzanine cards align with the I/O modules actually installed. Budget the enclosure's idle draw honestly — the shared infrastructure sips hundreds of watts before the first blade boots. And buy blades populated: their CPUs and DIMMs are standard parts, but a bare blade plus retail components rarely beats a loaded one's price. Done right, an M630-filled enclosure remains the cheapest rack of compute money can buy — with the M640 as the selective upgrade where ESXi 8 or newer fabrics demand it.