This motherboard certainly falls in the category of unique, if not borderline “wild” for a server motherboard design. One of the major challenges with current-generation server CPUs is that the CPU socket and the number of DIMM slots and PCIe lanes have gone up significantly, as has power. As a result, while mATX may have been common in the Xeon E5 generation, it has been less commonplace with the newer generations of CPUs. ASRock Rack, however, has taken the challenge of fitting an AMD EPYC 7002/ 7003 system into a mATX motherboard. That is the story of the ASRock Rack ROMED6U-2L2T which we are now going to review.
ASRock Rack ROMED6U-2L2T Overview
The motherboard itself is a relatively standard mATX size motherboard which is 9.6” x 9.6” (244mm x 244mm.) This is very interesting since that means it will fit in a variety of different chassis. It also poses a challenge since it restricts the total surface area ASRock rack has to place components. At the same time, ASRock Rack almost maximized a single-socket AMD EPYC 7002/7003 platform even in this small form factor.
For the CPU support, officially this supports the AMD EPYC 7002 and EPYC 7003 series. We started using the EPYC 7002 series for our review, then used an upgraded firmware package to add EPYC 7003 series processors. At the time we are writing (and we will check this on the day the review goes live) the only available EPYC 7003 firmware is designated as “lab firmware.” We confirmed this firmware worked with the EPYC 7713 but would caution our readers to check what is the most current version supported if they are reading this review in the future to make a purchasing decision.
This also shows us perhaps the biggest trade-off with this motherboard. An AMD EPYC 7002/ 7003 CPU can support up to 8 channels of memory in two DIMMs per channel (2DPC) mode. Given the space limitations, we get only six DIMM slots for six-channel memory. This does mean that we are practically limited to 75% of the total memory bandwidth available in this platform. The other way to view it, however, is that compared to a 2nd Generation Intel Xeon Scalable part we have the same number of channels but speeds supported up to DDR4-3200 so there is still some benefit to the EPYC platform here. The slots support the standard set of EPYC memory options such as ECC memory, RDIMMs, and LRDIMMs. We see 6x 16GB, 6x 32GB, and 6x 64GB being popular options here, but one can go higher.
The cooling is set up for standard front-to-rear airflow. To power fans, we get a total of six 4-pin PWM fan headers. On many compact motherboards, we will see this number cut to something like four headers to save space. ASRock lists the EPYC 7H12 as compatible (we could not test this) so with 280W TDP CPUs and the potential for many PCIe devices, cooling is going to be important in systems built around this platform.
While ASRock certainly had to compromise on the memory slot configuration, it did not have to do so on the rest of the I/O configuration. For PCIe slots we get four slots which is common on mATX motherboards. The difference is that these are PCIe Gen4 x16 slots and all have full x16 electrical interfaces to the CPU. On some of the more consumer motherboards, we see many PCIe x16 slots with shared links to the CPU. That is not the case here since this only uses 64 of the platform’s 128 PCIe lanes.
Next to the PCIe slots, we are just going to quickly note the ROMED6U-2L2T uses an ASPEED AST2500 BMC. If you are unfamiliar with the BMC in a server, see our article: Explaining the Baseboard Management Controller or BMC in Servers. This is what provides out-of-band management functionality.
Next, there is an M.2 2280 slot. This goes just behind the four PCIe slots and near the storage I/O interfaces.
There are also two 7-pin SATA ports. If you simply need a SATA port or two for boot, then these are the options.
Then we get to what may be the most special feature of this platform, the rest of the I/O. As a fair warning, on the next page, we are going to have the block diagram for this motherboard. It may be worthwhile opening page two in a side-by-side tab if you want to trace through this.
There are a total of three MiniSAS HD and Slimline NVMe connectors on the motherboard.
Even beyond the two onboard SATA ports and the M.2 slot, there is a lot of storage connectivity. The three MiniSAS HD connectors each provide four SATA ports for a total of twelve from those.
One can also see three Slimline NVMe connectors. Each of these is PCIe Gen4 x8 capable, which means one can use them to connect to backplanes for NVMe SSDs, or other PCIe devices. One of the Slimline ports can also be used for 8x SATA. We ordered a cable via Aliexpress to try the 8x SATA but 5 weeks in, it has still not arrived so we are going to have to assume the block diagram is correct on this one.
Underneath the board, there is actually a second M.2 slot, however, we did not get to test this one.
Overall, ASRock Rack is exposing almost all of the 128x high-speed I/O lanes as either PCIe or SATA III on this platform. Many larger ATX motherboards do not even do this.
Given the expansive I/O on the rest of the motherboard, one may assume basic I/O on this system. We have a standard I/O set with two USB 3 ports and an out-of-band management port for the BMC. There is a legacy VGA port for basic connectivity. 1GbE connectivity is powered by dual Intel i210 controllers. The nice, and perhaps a surprising feature, is the dual 10Gbase-T ports powered by an Intel X710-AT2 controller. The heatsink shown below between the VGA port and the SP3 CPU socket cools the X710 NIC. As a result, there is no room for a serial console output port on the rear I/O block.
On the bottom edge of the motherboard, there is a USB 3.0 front panel header oriented parallel to the motherboard PCB plane. We will simply note that you may need to check for clearance on this as well as the MiniSAS HD and Slimline 8i ports that come off of the other edge of the motherboard as it may be a challenge to use the ports in tight cases.
Then things get a bit more special. One will notice that we do not have a standard ATX power supply connector in this system. Instead, this can be DC-powered via the two 8-pin 12V DC IN in or using a standard ATX power supply using a 24-pin to 4-pin converter. One still needs to connect 8-pin power with the 4-pin power converter though. Our motherboard that ASRock Rack sent had this 24 to 4 pin converter in the box. (Apologies for how dark this photo is, the white connector was overexposed otherwise.)
Our box also had a MiniSAS HD to 4x SATA breakout cable, but the more interesting inclusion was this cable. There is an additional output on the motherboard that can supply power. This is especially useful if using a DC power input where one may not have the SATA power cable assortment found on ATX power supplies. The cable provides two sets of three SATA power connections for a total of six.
A quick word of warning here, one should be careful to use the 24-pin to 4-pin converter and this SATA power cable on the correct 4-pin headers. As one can imagine, using them incorrectly could cause damage to the motherboard. That is why we are showing these installed.
Next, let us get to the block diagram before we get to the management and the remainder of our review.