ASRock Rack DMRD16-2L+ exposes 128 PCIe Gen6 lanes

By Grace Kim

ASRock Rack's DMRD16-2L+ exposes 128 PCIe (Peripheral Component Interconnect Express) 6.0/CXL (Compute Express Link) 3.0 lanes through 16 MCIO connectors, as shown at the Open Compute Project (OCP) Summit 2026. The single-socket EEB (a 12-by-13-inch board format) targets Intel's Diamond Rapids Xeon platform and places 16 DDR5 DIMM (dual in-line memory module) slots in a one-DIMM-per-channel (1DPC) layout.

Memory configuration and module support

The 16 slots form two banks around the large processor socket, giving the CPU one module on each memory channel. The socket has a cover that locks with a twist rather than a straight pull, according to the board demonstration.

ASRock Rack says it supports three module types:

• Registered DIMMs (RDIMMs): "up to 128GB at max 8000MT/s."
• Multiplexed-rank DIMMs (MRDIMMs): "up to 128GB at max 12800MT/s."
• MRDIMM 2U modules: "up to 256GB," with a maximum rated speed of 12800MT/s.

Here, MT/s means million transfers per second. The listed per-module capacity ceiling is 128GB for RDIMMs and MRDIMMs, and 256GB for MRDIMM 2U modules. The two MRDIMM families also carry the higher 12800MT/s maximum, compared with 8000MT/s for RDIMMs.

Expansion architecture

The DMRD16-2L+ has no conventional PCIe CEM (card-edge module) add-in slots and no OCP NIC 3.0 (network interface card) connector. All PCIe expansion goes by wire: Gen6 I/O must pass through MCIO (high-speed mezzanine connector) links rather than a standard card slot.

Black MCIO x8 connectors line the I/O side. Up to 16 can be used across the board, and each is rated for PCIe 6.0 or CXL 3.0 traffic at x8 width, eight lanes per link. Sixteen x8 links provide the stated aggregate of 128 PCIe Gen6 or CXL 3.0 lanes.

The board's reliance on MCIO marks a practical shift in server integration. The accompanying hardware analysis said: "We have talked about PCIe signaling challenges since Ice Lake and Gen4, but with Gen6, we can see clear signs of the move to more cables." No add-in slot remains as an alternative to those wired connections.

Storage and management

Local storage comes from a single M-key M.2 slot operating at PCIe 5.0 x4, four lanes. It accepts M.2 22110, 2280 and 2260 drives.

Management hardware consists of an ASPEED AST2700 BMC (baseboard management controller). ASRock Rack also provides a dedicated IPMI (Intelligent Platform Management Interface) port via the Realtek RTL8211F, plus two RJ45 1GbE (gigabit Ethernet) ports driven by an Intel I350 controller for basic network connectivity.

Rear and internal I/O

The rear cluster has two USB 3.2 Gen1 Type-A ports and a DB15 VGA connector. An internal 19-pin header adds two USB 3.2 Gen1 ports. The board also provides a separate internal video header, one COM serial header, and a socket for a 13-pin SPI (Serial Peripheral Interface) TPM (Trusted Platform Module).

What does this change for server builders?

It narrows expansion to a cabled MCIO architecture while making Diamond Rapids' 16-channel memory scale physically explicit. Integrators cannot rely on conventional PCIe CEM card positions or the OCP NIC 3.0 connector; all Gen6 I/O must be planned around up to 16 x8 MCIO links and their cable routing.

The memory side follows the board's high-density layout. Intel had discussed a 16-channel Diamond Rapids design for some time, but the DMRD16-2L+ places one DIMM per channel in two banks around a single socket, with 16 physical slots in total. The result is a board that reaches 128 PCIe 6.0/CXL 3.0 lanes and supports module speeds up to 12800MT/s, but requires cabling designs built around wiring rather than removable cards.