Small ITX boards for Am4 with split support options
Small ITX boards for Am4 with split support options
You're aiming to set up a new ITX-based home server. The PCIe split matters since you plan to run multiple NVMe drives and other peripherals like SATA or GigE cards. I'm thinking AM4 might be a good fit because Intel limited desktop LGA1700 chipsets to x8x8. LGA1200 could work if you need higher density, but finding z590 ITX boards is tough these days. AM4 offers more flexibility, though it depends on the vendor adding support in the BIOS. It's hard to know what most boards can handle without checking the specs directly.
Do you have any of these ITX boards with recent BIOS updates? Please share the model, BIOS version, and how much support each supports (x8x8, x8x4x4, or x4x4x4x4).
For reference, ASUS ROG Strix B550-I, GAMING models, MSI MPG B550I, and others are mentioned. I saw a guide that says the B550 supports x8x4x4 and the X570 doesn't, but I'm curious if that's still accurate. You're also considering a card with high bifurcation using an ASMedia switch—though many options cost more than $$$$. The QNAP QM2-4P-384 is one choice, but it only supports up to x8x4x4x4, which isn't ideal for heavy NVMe workloads.
I currently have a mATX setup but it doesn’t fit the space I need, so I’m looking for a more compact option. This feature is quite vague, making it tough to understand exactly what’s required. It looks like manufacturers sometimes release boards without this component and then add it later in BIOS updates, which complicates things further.
The tiniest case I’ve seen is a Kolink satellite. There might be even smaller designs out there. If this isn’t about a case issue but a board issue, it could be different. The board I’m using right now is a Thermaltake Corev21—looks like two satellites stacked together. It’s wider but much shorter than a regular case, kind of like an elongated cube. There was a format called “pizza box” that used very specific power supplies. It was close to 1U in thickness, meaning at least 1U no matter the board size. The motherboard and cooler are about 1U, plus the PSU. I think ATX is around 2U, so the thickness (or width if you flip it) changes with different form factors, but the depth stays similar—around 1U plus whatever PSU size you have. Updated January 6, 2023 by Bombastinator
So after a lot of digging and decompiling several BIOS files . This is what I managed to work out. Just keep in mind that if you use an APU (eg 5600G or similar) then I believe you loose one x4 which is strange because the GPU is internally connected via the infinity fabric so it's not clear to me why this limitation exists. I logged a ticket with AMD and if they respond I will update this thread. It will also be interesting to see if this is the case with the AM5 platform. I hope this is of help to someone else since it probably took the better part of a day. Model Chipset Bifucation Ethernet M.2 SATA ASUS ROG Strix B550-I Gaming B550 2x8, 1x8/2x4 Intel i225 Front & Back 4 ASUS ROG Strix X570-I Gaming X570 1x16 Intel i211 Front & Back 4 MSI MPG B550I Gaming Edge Max WIFI B550 2x8, 1x8/2x4, 4x4 Realtek 8125B Front & Back 4 MSI MPG B550I Gaming Edge WIFI B550 2x8, 1x8/2x4, 4x4 Realtek 8125B Front & Back 4 ASRock Phantom Gaming-ITX/Ax B550 2x8, 1x8/2x4, 4x4 Intel i225 Front & Back 4 ASRock Phantom Gaming-ITX/TB3 X570 2x8, 1x8/2x4, 4x4 Intel i211 Back Only 4 ASRock B550M-ITX/ac B550 2x8 Realtek 8111H Front Only 4 Gigabyte B550I Aorus Pro AX (v1.2) B550 2x8, 1x8/2x4, 4x4 Realtek 8125 Front & Back 4 Gigabyte X570 I AORUS PRO WIFI (v1.0) X570 2x8, 1x8/2x4, 4x4 Intel 1Gb Front & Back 4 Gigabyte X570SI AORUS PRO AX (v1.1) X570 2x8, 1x8/2x4, 4x4 Intel 2.5Gb Front & Back 4
It’s an exceptionally odd requirement. Itx tends to cost more than microATX due to its larger PCIe slots, making it simpler. Those aiming for industrial use will often pick microATX despite needing SFF. Only a niche group would pay a 40% higher price for a 20% smaller size—mostly regular consumers. Edited January 13, 2023 by Bombastinator
I'm not sure I would classify bifurcation as an industrial feature, more in the enthusiast/server realm. I have been using it for years in a number of servers running virtual machines. It's a great way to give multiple VMs access to their own dedicated PCIe x4 slots for access to different devices (NVMe, Ethernet, Coral TPUs, SATA controllers, etc). In this case I'm just downsizing a home file server with 4 x 12TB drives and 12TB NVMe. The NMVe drives are divided into 3 pools, one with redundancy (for critical VM vdisks, dockers, etc) and two without (NVR and Timecapsule backups). It's pretty tricky to get 4-6 NVMe drives into a single system without bifurcation. Can't wait for more affordable 4 and 8TB NVMe drives to hit the market. For anyone who is interested in this stuff, I have a threat over on the AMD forum with more details.
There are widely used industrial uses for this technology. Cryptomining is one such application, but there are various methods available. Proof of stake, for example, demands significant storage capacity, yet it didn’t fail—it actually stopped when Ethereum shifted from proof of work to proof of stake. There may even be Linux distributions built around these systems. The availability and pricing remain uncertain; some boards might be costly due to high demand from crypto miners, while others could be affordable if many small systems enter the market. I’m unsure about exact costs or stock levels but think it’s likely a mix of both scenarios. I steer clear of this topic altogether, though I acknowledge its existence. If it’s hard to find, it’s not because it’s unpopular—it’s simply in high demand. A good starting point would be AliExpress, but note the distinction between microATX and miniITX listings. ITX boards are generally less common for industrial use, as they’re more suited to budget builds. There could still be options, especially if large quantities of inexpensive components are used. Updated: February 7, 2023 by Bombastinator
This individual seems mistaken about the significance of thirty thousand posts. The inclusion of Epyc and Xeon chips in mini-ITX units still matters, even without bifurcation. Even without that, if someone needs a 10GbE or 25GbE card, it raises questions. In 2023, this isn't considered "industrial" or extremely unusual.
The calculations show a substantial gap—9.6 by 9.6 equals 92.16 for MATX and 44.89 for ITX, a difference of about 47.27 square inches. That’s why mATX cases appear much larger than mini-ITX ones; they’re designed to be bigger.
The idea of a "20% size reduction" is misleading. The actual math suggests a much higher percentage change. Perhaps the author misunderstood the numbers.
What’s odd is that this person seems to have the opposite perspective. In real industry, customized hardware exists, so such differences aren’t trivial. For those who’ve worked with mini-ITX for years, they’ll know that even small changes matter—30% is a big deal, and 10% is already concerning. If you’ve been using mini-ITX, you’ll see how much bigger mini-iTX already is, making further expansion unnecessary.