ASRock Rack GENOAD8X-2T/BCM Topology
Given just how much I/O there is on this platform, it is important to take a look at the block diagram.
While everything ultimately goes back to the single AMD EPYC CPU, several of the PCIe Gen5 lanes also have options to power the MCIO connectors and M.2 slots, but that depends on how they are used.
The other big point that one will want to know is that the NCSI connection is to the second LAN port on the Broadcom 10Gbase-T NIC. That is how the BMC communicates with the 10Gbase-T NICs and is important for some folks.
ASRock Rack GENOAD8X-2T/BCM Performance
One of the big open questions with this platform was the performance. Especially given the 8-channel memory configuration. We ran a 96-core AMD EPYC through a suite of benchmarks to gauge the impact.
Overall, the performance was good, but there was some loss simply due to having fewer memory channels available. At the same time, it is important to take a step back here. Having a bit less performance than a reference Genoa platform still means it can be as fast, or faster than many dual-socket servers from even a generation ago. What is more, this is one of the few options that has this much PCIe Gen5 connectivity exposed via PCIe slots.
One way to look at the above is, of course, shorter bars are shorter. The other way to look at this is it is a lot of performance in a platform that can be installed into many different chassis and locations.
This is a motherboard that we absolutely love. While some may bemoan the loss of an ATX form factor, the fact is that newer CPUs need more physical motherboard space to provide PCIe I/O along with the massive processors and memory loadouts. Bryan actually tried putting together a workstation build with the ASRock Rack GENOAD8UD-2T/X550 but the lack of USB I/O was a challenge there. Having used this motherboard, perhaps we will resurrect that project. In either case, that brings us to the point of this, it is one of the few Genoa motherboards that is a standard non-proprietary form factor. That means it can be integrated into a variety of projects.
The AMD Socket SP5 is ultra-versatile. It can handle standard AMD EPYC Genoa CPUs, high-cache Genoa-X parts, and even the high-core count Bergamo parts.
Aside from having up to 128 cores / 256 threads in the single socket the PCIe Gen5 I/O is going to make a segment of our readers extremely excited. That is a TON of PCIe connectivity for a single-socket platform. As PCIe Gen5 devices become more commonplace, this motherboard has plenty of room to expand.
On the subject of the key lessons learned from that PCIe I/O is what is required to make that happen on a motherboard like this. There is a large array of Phison redrivers on this motherboard just to help with PCIe Gen5 signal integrity. We have been talking about the looming challenges with PCIe signal integrity as speeds increase for years, and this is a great example of its impact. One thing to be certain of is that this is one of the biggest features of this board. Having redrivers in the chain adds cost, but it boosts signal integrity. A cheaper option would be to skip the redrivers and just hope that devices connect properly. It is great to see ASRock Rack went for the higher-end solution on this motherboard.
It is hard to fathom that the ASRock Rack GENOAD8X-2T/BCM is an EEB-size motherboard that still had to reduce DDR5 DIMM slots to eight in order to fit everything into a non-proprietary form factor. Still, that is what we have here and the results are awesome. When we first saw this board in trade show booths, we knew we needed to show our readers it. Once we got to use it, it certainly met all of our lofty expectations for an awesome AMD EPYC powered PCIe Gen5 platform.