ASRock Rack EPC621D4I-2M Motherboard Review


ASRock Rack EPC621D4I-2M Motherboard Specifications

Here are the key specs for the ASRock Rack EPC621D4I-2M motherboard:

  • Model Name: Asrock Rack EPC621D4I-2M
  • Form Factor: Mini ITX
  • Dimension: 6.7″ x 6.7″ (17.02cm x 17.02cm)
  • CPU: Intel Xeon Scalable (1st and 2nd Gen)
  • Socket: LGA3647
  • Chipset: Intel C621
  • Memory Slots: 4x 260 pin DDR4 SODIMM (UDIMM/ RDIMM and ECC supported)
  • Memory Capacities: Up to 32GB per DIMM
  • Memory Speeds: Up to DDR4-2933 with matching Intel SKUs supporting speeds
  • Expansion Slot: 1x PCIe Gen3 x16
  • SATA: 1x SATADOM (powered), 1x SFF-8643 4-port header
  • M.2: 2x M.2 SATA/ NVMe supported
  • LAN: Intel C621-based Intel X722 MAC for 2x 1GbE
  • BMC: Aspeed AST2500 with 256GB DDR4
  • Rear I/O: 1x D-Sub, 2x USB 3.1 Gen1, 2x RJ54 Ethernet

We noticed that ASRock Rack produces this class of motherboard in two versions, the EPC621D4I-2M and the EPC621D6I. While we are reviewing the EPC621D4I-2M here, the EPC621D6I sacrifices the two M.2 SATA ports for two additional SODIMM slots giving it a total of six. That means more memory capacity but less storage capacity.

ASRock Rack EPC621D4I-2M Block Diagram

Here is the block diagram for the ASRock Rack EPC621D4I-2M:

ASRock Rack EPC621D4I 2M Block Diagram
ASRock Rack EPC621D4I 2M Block Diagram

One can see that the server is using the Intel Xeon SP Lewisburg C621 PCH to handle most of the I/O except for the PCIe Gen3 x16 slot and the DRAM. In most servers, we see more CPU PCIe lanes used, however, the mITX form factor is very limiting here.

ASRock Rack EPC621D4I-2M Motherboard Test Configuration

We set the system up using an active cooler just to show what is possible even without chassis fans.

ASRock Rack EPC621D4I 2M Test Setup
ASRock Rack EPC621D4I 2M Test Setup

Here we have our ASRock Rack EPC621D4I-2M motherboard setup and using a Dynatron LGA 3647 B5 heat sink which is massive compared to the motherboard. The B5 is used in 2U servers and a good option for that size using active fans to aid in cooling. Most of the systems that would use the EPC621D4I-2M might fit into a 1U server where a passive heat sink cooled by the midplane fans would be used. With only a motherboard available for use to review the B5 made sense. Here is the rest of the configuration:

  • Motherboard: ASRock Rack EPC621D4I-2M Motherboard
  • CPU: Intel Xeon Gold 6134 8 core / 16 threads
  • GPU: ASUS Turbo RTX2060 Blower
  • Cooling: Dynatron LGA 3647 B5
  • RAM: 4x Crucial 8GB SODIMM DDR4-2666 (32GB Total)
  • SSD: SanDisk X210 512GB
  • OS: Windows 10 Pro

We started testing this motherboard before the 2nd Gen Intel Xeon Scalable Launch so we did a lot of the screenshot and setup work with a 1st generation chip. We were able to use the 2nd generation chips in this platform after the launch.

Intel Xeon Gold 6134
Intel Xeon Gold 6134

The Intel Xeon Gold 6134 is the same CPU we use on our ASUS WS C621E SAGE workstation motherboard test bench. The TDP of 130 watts is a bit high for a mITX system. We can see those in the dedicated hosting market using lower TDP Intel Xeon Silver and Intel Xeon Gold CPUs.

For our first set of tests we wanted to see if the single PCIe slot supported external GPUs. We installed our ASUS Turbo-RTX2060-6G Blower graphics card as proceeded to boot into Server 2012 R2 and even Windows 10 Pro without any issues. Clearly, this GPU is enormous for a system like this; most users would use KVM and use the single PCIe slot for a 10GbE NIC or a RAID controller card. While we had these OS’s up and running, we ran a few benchmarks to check out what numbers these give.

AIDA64 Memory Test

AIDA64 memory bandwidth benchmarks (Memory Read, Memory Write, and Memory Copy) measure the maximum achievable memory data transfer bandwidth.

ASRock Rack EPC621D4I 2M AIDA64 Memory
ASRock Rack EPC621D4I 2M AIDA64 Memory

With 4x Sticks Crucial 8GB SODIMM DDR4-2666 installed we see excellent memory performance for a platform like this.

Geekbench 4

ASRock Rack EPC621D4I 2M Geekbench
ASRock Rack EPC621D4I 2M Geekbench

Performance during our initial setup with the Intel Xeon Gold 6134 processor was what we would expect from a larger server. The small form factor worked well here.

Next, we are going to look at the CPU benchmarks running under Ubuntu.


  1. Pls review ASRock Rack D2143D4I2-2T or Supermicro Edge Computing/Gateway lineup like SuperServer E403-9D-8CN-FN13TP with X11SDW-8C-TP13F.

  2. “We wanted to get this review complete instead of waiting for some of the higher end SKUs like the Intel Xeon Platinum 8280 and Platinum 8276L CPUs available”
    while all of my skylake-sp supports UDIMM, my Cascade-Lake-SP don’t support UDIMM.
    in theory this can’t work…

  3. aus dem ASRock Rack PDF(EPC621D4I-2M – EPC621D6I)
    “4 DIMM slots, Supports Quad Channel DDR4 2993/2666/2400 ECC SO R DIMM, ECC SO DIMM, and non-ECC SO DIMM (Max. 64GB)”
    Es gibt SO R DIMM ????? wo ?

  4. Hello Patrick,
    There is some confusion regarding the ILM of this socket. You mention that it is square and even reference the Dynatron B13. the folks from ASRock Rack and Dynatron were saying that it was a narrow ILM. Can you confirm which type that MB uses?


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