Rack GENOAD8UD-2T/X550 Genoa Motherboard

The form factor. This is not a 9.6″ x 9.6″ mATX form factor or a 12″ x 9″ ATX form factor. Instead, it is 10.4″ x 10.5″. Even with a non-standard size, even finding room for the motherboard standoff mounting points appears as though it was more challenging for ASRock Rack. That non-standard chassis also meant that the first chassis we tried to build this motherboard into did not fit.

On the right edge of the motherboard, we can see six five-pin fan headers. That is a fairly good set since we expect this platform to need cooling. A third trade-off with the platform is the power situation. Given physical size constraints, the motherboard does not have a standard 24-pin power connector. Instead, it has three 12V CPU power inputs. That does mean it also supports DC input if one has a large 12V DC power source. Many power supplies do not have three 12V inputs, and one needs to use an adapter to perform normal power functions from a standard power supply’s 24-pin ATX connector.

While that may sound like a lot of trade-offs, there are some areas where this blows away a standard mATX motherboard beyond just the core counts. For example, there are four PCIe expansion slots. These are not just for show, each is a PCIe Gen5 x16 slot. That is only half of the EPYC Genoa’s PCIe Gen5 slot capacity. The Gen5 x16 slots are also the lanes from the EPYC CPU that support CXL 1.1 Type-3 devices. See Compute Express Link CXL 3.0 as our latest guide in that area. We did not get to test these slots with the CXL devices, however, we are still in the early days of devices and support so our readers should view CXL support as a bit of a forward-looking feature.

Having 64x PCIe Gen5/ CXL lanes is great, but there is a lot more. Next to these slots are two PCIe Gen4 x4 M.2 slots for boot SSDs.

There are headers and a POST code display on the bottom edge of the motherboard, but the other big feature is on the right edge. There are a total of four PCIe Gen5 x8 MCIO connectors and one x4 MCIO. MCIO is a newer connector for the PCIe Gen5/ CXL generation, however, these are PCIe Gen5. Two of the x8 connectors can also run as 8x SATA III headers, but our sense is that it is more efficient to use a HBA to connect to lower-speed SATA devices. There are no 7-pin SATA connectors on this motherboard which feels refreshingly modern.

One nice feature is that ASRock has these MCIO connectors that are in line with the PCIe x16 slots parallel to the motherboard. It also means that if you plan to use this motherboard in a chassis there is a bit of extra chassis clearance needed to use these ports.

Here is a view from the other angle.

Here is a view looking at the motherboard from the standard airflow direction to give a sense of the profile and how the slots and connectors align.

Next to the CPU we have the VRM heatsinks but also a heatsink for the Intel X550 NIC. This platform has 10Gbase-T networking. There is not a lot of space, so having at least 10GbE instead of 1GbE is welcome.

Aside from the two RJ45 10Gbase-T ports, there is not a lot else on the rear I/O side of the motherboard. A VGA port and two USB 3 ports provide local access. A management port provides out-of-band access to the platform.