Mini ITX AM4 boards with Bifurcation Support

[cat2devnull]

Looking to build a new home server based on ITX.
PCIe bifurcation is important because I intend to run a bunch of NVME drives an other peripherals (SATA/GigE cards).
I'm probably looking at AM4 because Intel has restricted the the desktop LGA1700 chipsets to x8x8.
I would consider LGA1200 since they can do x8x4x4 but z590 ITX boards are almost impossible to find these days.

 

AM4 has no such limitation and can in theory do x4x4x4x4 but it is up to the board vendor to add support in the BIOS.
Unfortunately it is tricky to work out what most can support because it isn't the sort of thing they put on the specs page.

Does anyone here have any of the following ITX boards (with recent BIOS) and can confirm what they can support.
Please respond with the model of board, BIOS version and level of support (x8x8, x8x4x4 or x4x4x4x4).

 

ASUS ROG STRIX B550-I GAMING

ASUS ROG Strix X570-I Gaming
MSI MPG B550I GAMING EDGE MAX WIFI
MSI MPG B550I GAMING EDGE WIFI
ASRock Phantom Gaming-ITX/Ax
ASRock Phantom Gaming-ITX/TB3 
ASRock B550M-ITX/ac

Gigabyte X570SI AORUS PRO AX

Gigabyte X570 I AORUS PRO WIFI

 

ASUS publish this guide which shows their B550 supports x8x4x4 and the x570 does not but I always wonder if this is up to date?

I could look at a card that can do x16 bifurcation (using an ASMedia PCIe switch) but I am not aware of many that don't cost $$$.
The QNAP QM2-4P-384 QUAD M.2 Card is one option but it only uses x8 to x4x4x4x4 which is a bit of a waste of bandwidth.
Thanks,

[Bombastinator]

Does it have to be itx?  How about microATX?

 

it’s bigger, but not a whole lot bigger, and it may be a lot easier to do.

Edited January 5, 2023 by Bombastinator

[cat2devnull]

I currently have a mATX system and it doesn't fit where I need it to go so trying to find a downsized solution that will work.
It's just a rather abstract feature that is hard to get details about.
Also it seems that vendors often release boards without it and then add it in later BIOS updates which makes it even harder to work out.

[Bombastinator]

2 hours ago, cat2devnull said:

I currently have a mATX system and it doesn't fit where I need it to go so trying to find a downsized solution that will work.
It's just a rather abstract feature that is hard to get details about.
Also it seems that vendors often release boards without it and then add it in later BIOS updates which makes it even harder to work out.

The smallest matx case I know of is that I know of is a kolink satalite. There is probably smaller stuff though.  If this isn’t a case problem but a board problem it might not then.the case I am currently using is a thermaltake corev21 which looks like it’s more-or-less 2 satellites stacked on top of each other.  So wider but a lot shorter than a traditional case.  Sort of an elongated cube. 
 

there used to be a format called the “pizza box” which used very specialized power supplies.  It was pretty close to 1U so no matter what no less than 1U for thickness.  So there’s the motherboard and cooler, which is pretty close to 1U, plus the power supply.  Iirc atx is 2U so That’s thickness (or width if you turn the think on it’s side) with different board form factors you more or less vary the depth and width/height, but the thickness stays the same: around 1U.+ whatever PSU form factor.

Edited January 6, 2023 by Bombastinator

[cat2devnull]

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

[Bombastinator]

It’s just a really really unusual need.  Itx is generally MORE expensive than microATX which has more pcie slots so it’s easier.  So someone wanting to do something industrial, which is what bifurcation is usually for, will go for microATX over itx even if they need SFF. The only people wo want to pay a 40% premium for a 20% size reduction are consumers generally.

Edited January 13, 2023 by Bombastinator

[cat2devnull]

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.

On 1/14/2023 at 9:47 AM, cat2devnull said:

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.

For anyone who is interested in this stuff, I have a threat over on the AMD forum with more details.
 

[Bombastinator]

Oh there are totally common industrial applications for that, One of them is cryptomining.  There are a bunch of kinds of cryptomining though.  One of them is proof of stake which requires absolutely absurd amounts of storage space.  It is NOT the section of cryptomining that crashed though.  In fact it crashed because etherium changed from proof of work to proof of stake. There will likely even be Linux distros specifically designed to use them.  So are there such boards made? Almost certainly.  I have no idea what they cost and how available they are atm though.  It could be they’re incredibly expensive because cryptobros are buying them hand over fist.  It could be that they’re incredibly cheap because proof of stake is only really viable for people that already have large numbers of hashes, so small cheap systems like there might be on matx are flooding the market.  I just have no idea. I avoid that whole thing entirely.  That they exist though I have little doubt. If they’re hard to get it’s not because they’re unpopular it’s because they ARE popular. One place to look is aliexpress.  
 

NOTE: I made this post because I somehow read as microATX not miniITX and only looked at the new post. There will be a lot fewer itx boards.  Itx isn’t industrial generally. Folks want cheap and itx is more expensive to build because there’s so little space.  There probably are a bunch though. If there are huge numbers that are really cheap it’s very possible they have ONLY the bits required for proof of stake though because fewer cheaper larger components can be used.

Edited February 7, 2023 by Bombastinator

[LinusGuessTips]

On 1/13/2023 at 6:34 PM, Bombastinator said:

It’s just a really really unusual need.  Itx is generally MORE expensive than microATX which has more pcie slots so it’s easier.  So someone wanting to do something industrial, which is what bifurcation is usually for, will go for microATX over itx even if they need SFF. The only people wo want to pay a 40% premium for a 20% size reduction are consumers generally.

How is this person so wrong with _THIRTY_THOUSAND_ posts?

 

"Industrial" need? Well, there's embedded Epyc's and Xeon's in mini-ITX with bifurcation but, even if there wasn't, what if someone wants to video edit with a 10gbe or 25gbe card? It's 2023, this is not "industrial" or "really really unusual".

 

9.6 * 9.6 = 92.16 (mATX)

6.7 * 6.7 = 44.89 (ITX)

That's a difference of 47.27, mATX is over double the square inches of ITX. In the end, this is why mATX cases always look huge compared to mini-ITX cases, because they are!

 

"20% size reduction"

So mATX reduced to ITX size is a 20% difference?

6.7 / .8 = 8.375 (wrong, not 9.6)

correct: 1 - (6.7 / 9.6) = 0.302083333 ... 30%

Maybe they meant 20% increase from ITX?

6.7 * 1.2 = 8.04  (wrong, not 9.6)

correct: 9.6 / 6.7 = 1.432835821 .... 43%

 

If you're going to be wrong at least put some effort into being wrong! The ironic thing is that this person has things backwards. In the "industry" you'll have fully customized hardware,  so bifurcation isn't needed. Consumers don't customize hardware so this design difference creates a zero-sum position irrespective of what the consumer does or doesn't do with the hardware, thus bifurcation needs to be implemented by the manufacturer.

 

It's completely lost on a lot of people that if you're building with mini-ITX, differences of 30% are huge, enormous, crazy! Even 10% is alarming, it's ridiculous to believe otherwise. If you've been building with mini-ITX for several years, you'll understand that mini-iTX is already pretty large itself so there's no desire,  at all, to make it any bigger.