Concept Flex-ITX motherboard form factor concept

Necere

SFF Guru
Original poster
Feb 22, 2015
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So @Wahaha360 is in contact with some motherboard manufacturers, and beyond the usual suggestions (e.g. mDTX w/dual PCIe slots) one thing he's brought up with them is the possibility of adding a PCIe slot at an alternate location that would enable sandwich or console-style layouts without requiring expensive and potentially unreliable flexible PCIe risers. Along the same lines, I had this idea for a flexible form-factor based on mini-ITX:








Essentially, it replaces the PCIe slot on a mini-ITX board with a PCIe edge connector. This would allow for many more possibilities for the PCIe slot, simply by switching out an inexpensive and reliable PCB riser. Among them:
  • Standard mini-ITX w/traditional perpendicular PCIe slot
  • Using a long PCB riser to enable back-to-back sandwich-style layouts (like the A4, Ghost S1, etc.)
  • Using a long PCB riser to enable console-style layouts
  • Multiple PCIe slots via a riser supporting bifurcation
I should mention, since it isn't in my illustration (which is just a rough mockup to get the idea across) that the PCIe slots/risers would need to have some (standardized) means of securely mounting to the motherboard. Just to head off that specific critique.

Now, this is just an idea at this stage, and we have yet to get feedback on the engineering feasibility, but we thought it worthwhile to share it with the community. I think such a flexible motherboard form-factor would be of tremendous benefit to SFF case designers and users alike, as it would help to create a more accessible, standardized way of enabling a multitude of different SFF case layouts at a potentially lower cost.

Any feedback you might have is welcome.


To be clear, I'm introducing this as a concept for a new board form-factor that extends the functionality of mini-ITX, not as a wishlist of features people want for a specific motherboard. That should have its own thread if people want it.
 
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ZivZulander

Trash Compacter
Jan 12, 2020
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I like it. Simple, and it makes sense. How does the connector lock on/attach to the slot?

EDIT: oops, reading fail on my part 😁
 

gwertheim

Master of Cramming
Gold Supporter
Nov 27, 2017
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Could work, would you need to redesign the motherboard mount to accommodate the pcie slot?
 

Necere

SFF Guru
Original poster
Feb 22, 2015
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Any idea if something like internal USB4/Thunderbolt 3 riser could be done? My main issue with risers is the ribbon cables, many of which are too stiff and not easily routable.
Can you elaborate? Not sure what you're asking for.
 

Protools

Trash Compacter
Oct 10, 2018
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30
Looks neat, but I worry that various sandwich layout cases in the future
will have to be set on the PCIE riser PCB length without versatility.
 

ZivZulander

Trash Compacter
Jan 12, 2020
40
65
Can you elaborate? Not sure what you're asking for.
Something like this:
Amazon product
Except one end is to connect to USB 4.0/Thunderbolt 3 header on mobo and the other end is standard PCIe 3.0 or 4.0 x16. I have no idea if that could be done, but I assume the bandwidth could be there at least given that it's essentially what is done with eGPUs.

Might need another power cable as well, which is why I'm wondering if this could be something the mobo makers might be able to do.

Sorry if it's a dumb question, I just think ribbon cables should have died with IDE. 😛
 
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Necere

SFF Guru
Original poster
Feb 22, 2015
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Looks neat, but I worry that various sandwich layout cases in the future
will have to be set on the PCIE riser PCB length without versatility.
It would be trivial to make a riser with the slot farther up or down.

Something like this:
Amazon product
Except one end is to connect to USB 4.0/Thunderbolt 3 header on mobo and the other end is standard PCIe 3.0 or 4.0 x16. I have no idea if that could be done, but I assume the bandwidth could be there at least given that it's essentially what is done with eGPUs.

Might need another power cable as well, which is why I'm wondering if this could be something the mobo makers might be able to do.

Sorry if it's a dumb question, I just think ribbon cables should have died with IDE. 😛
That would require an active riser with more components and added bulk. The point of the concept is really to make it simpler, cheaper, and more reliable, so such a TB/USB to PCIe adapter wouldn't really fit here.
 

fabio

SFF Guru
Gold Supporter
Apr 6, 2016
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This is an amazing and simple idea!! Looking forward to follow the entire development!
 
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Goatee

Airflow Optimizer
Bronze Supporter
Jun 22, 2018
308
510
Love the idea. Is there a benifit in adopting a top mounted PCIE (rather than conventional bottom mounted) using the flexible mount approach? A bit like the PIO boards use? This would allow both CPU and GPU fans to face the same way.
 

newtothegame

Trash Compacter
Sep 1, 2018
48
58
Well done, it makes a lot of sense to design mini-ITX motherboards this way. All the best with the project.
 

ExplodingWaffle101

SFF Lingo Aficionado
May 11, 2018
114
69
would this be possible in console style layout with cpu/gpu facing same way?

i think this would actually be revolutionary, and as long as you got it working no problem with pcie4 (one benefit of pcb risers i can think of is being able to add retimers if needed) everyone should be on board, maybe even oems!
 

Analogue Blacksheep

Airflow Optimizer
Bronze Supporter
Dec 2, 2018
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@Necere Interesting concept, however where are you planning on putting the m.2 ports? Part of the reason why is if you have one on the back and you have a riser cable covering it wouldn't that cause thermal issues for the m.2?

When I still had the ZS-A4 DC, I spent some time looking at ways of moving the rear mounted M.2 away to another part of the case. I did look at an M.2 to OCuLink based solution but I never got the chance to test it as my motherboard didn't fit the case. There are also cables like this m.2 to u.2 cable which can also work. @fabio used one in his MI-6 build if you are looking for examples.

Then again, if we had some more motherboards with some native OCuLink or SAS ports like the recent Asrock Rack X570-I board that could solve the problem.
 
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duynguyenle

SFF Lingo Aficionado
Aug 20, 2019
121
108
I believe this already exist (motherboard with edge-aligned PCI express connector). I can't seem to find the link anymore, but I remember seeing one just like the concept you proposed. It's more or less a standard form factor except with the pcie connector mounted on the edge in-line with the plane of the board instead of otlrthogonal to the board surface.

IIRC its quite a popular form factor for Chinese Internet cafes because it allows for thinner case width (allowing them to cram more PC booths into the same floorspace)

I'll try and find that posting again after work