Over the last year, we've seen several B550 models, with the vast majority of these catering to desktop users and gamers looking for a cost-efficient option to use with AMD's Ryzen processors. Back in January, we reported that ASRock Rack had readied up a new B550 model with a more professional flavor, the B550D4-4L. The B550D4-4L features support with a broad range of AMD Ryzen processors, including 5000, 4000G, and 4000 Pro, with support for most 3000 series processors. Some of the board's core features include Gigabit Ethernet, support for 128 GB of DDR4 memory, and an ASPEED BMC controller for management over a network. We get to grips with the ASRock Rack B550D4-4L and see how it compares to other AM4 models in our latest motherboard review. It came with a few surprises as well.

ASRock Rack B550D4-4L Overview

Perhaps considered one of the most 'interesting' motherboards based on the B550 chipset is the ASRock Rack B550D4-4L. At the time of writing, the B550D4-4L is the only B550 board known to us that includes a BMC controller. It is designed to utilize the power and high-core count of AMD's Ryzen 5000 and 3000 desktop processors, with support also available for AMD's Ryzen Pro 4000 series and some Pro 3000 Processors.

The ASRock Rack B550D4-4L has a transposed AM4 socket and transposed memory slots

Looking at the overall design, it is focused on professional use and uses a standard green PCB. The B550D4-4L opts out of fanciful aesthetics and instead focuses on core functionality. Along the top is four memory slots which are horizontally mounted, with support for up to 128 GB DDR4-3200, both ECC with supported Ryzen Pro processors and non-ECC memory on the regular Ryzen desktop models. The B550D4-4L has one full-length PCIe 4.0 x16 slot and one half-length PCIe 4.0 slot. For storage, there's just one M.2 slot but is only capable of supporting PCIe 3.0 x4 or SATA drives, as well as six SATA ports, four from the chipset and two from an ASMedia controller.

The rear panel has four Intel Gigabit Ethernet ports, with a fifth Ethernet port for the board's ASPEED BMC controller, allowing remote access to the system over a network. Other connectivity includes an HDMI output for use with processors with integrated graphics and a D-Sub output (DB15) for the BMC, and four USB Type-A ports, two USB 3.2 G2, two USB 3.2 G1. ASRock Rack also includes a serial connector (DB9). The B550D4-4L also has a USB 3.2 G1 header providing a further two ports, a USB 2.0 header for two ports, and six 6-pin fan headers.

ASRock B550D4-4L Block Diagram

Looking at performance, the B550D4-4L was surprisingly competitive in our computational-focused benchmarks, with the board using AMD's Precision Boost Overdrive at default. This is above simply doing a good turbo, making the board perform a lot better than we would assume.

One downside in performance was perhaps the memory - it ran at DDR4-3200 CL22 as opposed to other B550 models we tested at DDR4-3200 CL16, and no matter what values we put in for the latencies, they stayed at JEDEC CL22.

The B550D4-4L also proved competitive in our system testing, with faster than expected POST time performance. It showed lower power consumption in long idle and idle power states than most boards, while power consumption at load was comparable with other models on test. The board's DPC latency performance isn't great, but it doesn't include any form of audio codec or audio output regardless.

The ASRock Rack B550D4-4L is a unique B550 model, with not much competition in the way of server-focused models. ASRock also has a model based on the propriety deep mini-ITX form factor, the B550D4ID-2L2T, which uses the B550 chipset for more professional level function. Unlike other B550 models, the B550D4-4L disables overclocking, which is understandable given its lack of heatsink capability on the power delivery, highlighting that this board isn't for pushing the boundaries or requires a system with strong airflow.

The real capability comes for users looking to build a Ryzen desktop-based server with the associated performance levels at default settings, along with added functionality for both Ryzen Pro series processors and the ASPEED BMC controller allows access and control of the system remotely. It's also the only B550 model to feature four dedicated Ethernet controllers, and it makes it one of the most interesting AM4 models we've received for review so far.

Read on for our extended analysis.

Visual Inspection
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  • fmyhr - Thursday, May 20, 2021 - link

    While this is true, AMD and motherboard manufacturers are distressingly cagey about whether ECC and ECC error reporting actually work. If you care about this, you need to do your own searches. There have been cases of ECC support being added or removed on successive motherboard BIOS revisions. The different mainstream mfgs have different attitudes regarding ECC RAM: MSI pretty much ignores it, Gigabyte says they support ECC on _some_ boards, Asus seems somewhat better, and ASRock appears to be the best bet. If only Supermicro would give us a non-Threadripper Ryzen board...
  • AntonErtl - Friday, May 21, 2021 - link

    AFAIK all ASUS (as well as all Asrock) boards support ECC. We have several servers with (working) ECC with Ryzen CPUs (without Pro): 1600X, 1800X, 3700X, 3900X, 5800X. If AMD sold the Pro models in retail and guaranteed ECC functionality, we would be willing to pay a little extra for that. As for the Pro models, I once compared the specification of one with the corresponding non-Pro model, and wrt ECC they were the same. Can anyone name a Pro model where AMD guarantees more ECC functionality?
  • mode_13h - Friday, May 21, 2021 - link

    The difference between ECC support of Pro and non-Pro CPUs is supposedly that AMD only tests and guarantees it on the Pros. For the non-Pro CPUs, it's up to the motherboard vendor to test and support.

    As for APUs, AMD disables ECC support on the non-Pro APUs. I guess that's because the main customers for APUs with ECC are corporations, and so it's like a favor to big OEMs, giving them a lock on the corporate market (since the Pro versions seem to be EOM-only).
  • mode_13h - Friday, May 21, 2021 - link

    > EOM-only

    typo: should be OEM-only.
  • Slash3 - Friday, May 21, 2021 - link

    Correct. The board does indeed support ECC in that way. Gavin misinterpreted the specifications; no idea why, as it is quite clear.


    "DDR4 288-pin ECC*/non-ECC UDIMM
    * For AMD Ryzen Desktop Processors with Radeon Graphics, ECC support is only with Processors with PRO technologies."

    Non-Pro APUs have always been the exception, and do not support ECC on any platform.
  • Jorgp2 - Friday, May 21, 2021 - link

    >Uhh.. ECC memory works just fine with bog standard (aka "not Pro") Ryzen CPU's and has LITERALLY since their launch in 2017.

    I don't think you understand what kind of board this is.

    If the data sheet says it only supports ECC for select SKUs, then it only supports ECC for select SKUs.
    There is no halfway for the target market.
  • leexgx - Friday, June 18, 2021 - link

    Ecc functionality still works even with the non-pro CPUs (just official stance is it doesn't work even thought it does, not like Intel where if its an i5 or higher ecc automatically doesn't work) ddr5 is going to change this problem with Intel as ecc is baked into ddr5 and can't be disabled and sold "as a enterprise" feature
  • MeJ - Friday, May 21, 2021 - link

    "The B550D4-4L also doesn't include integrated audio, so users looking to build an audio workstation will need to rely on external audio controllers."

    With respect, this comment is illogical. I have never heard of any DAWorkstation using on-board audio, and don't ever expect to. NOT having on-board audio to disable is a major advantage for a DAW. Also, the DPC issues here are perhaps characteristic of early drivers. There is no inherent reason I can see for this board to have worse performance than others with the same chipset... Is there? I agree that 10G would be preferred for a DAW.
  • mode_13h - Friday, May 21, 2021 - link

    Lol. Yeah, integrated audio on server boards that even have it tends to be a minimal implementation, with lots of crosstalk and interference.
  • mode_13h - Friday, May 21, 2021 - link

    ASPEED BMCs are such garbage. This has the same ARM11 core as a first gen Raspberry Pi. Just imagine how slow software rendering is on such a core, and that's the graphics performance you get on these things.

    I have an ASRock board with one of these BMCs, and 2D graphics even feels slow at 1024x768 (which is the resolution that the EDID of my analog KVM seems to advertise, even though the monitor is higher).

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