Motherboard Starting with the basics

Jdkell3

Minimal Tinkerer
Original poster
Aug 1, 2018
3
0
In getting into sff, there are a lot of choices of everything to choose from.

I thought I would start with what I want in my PC and go from there—starting with the motherboard.

Ideally I want to start with a motherboard with 2x PCIe 3x8 slots and more additional 3x8.

The two 3x8 slots to hold 1080ti’s and the other 3x8 to hold a 10Gb NIC.

I’d like to somehow have thunderbolt-3 and gave room for U.2 and maybe 4x 2.5” sata3 drives.


It’s asking a lot, but I think the first step is to find a small motherboard to support that, and then go from there. Unless you all also have recommendations on cases too.
 

Vlad502

Airflow Optimizer
Nov 4, 2017
256
206
I guess you mean PCI-E v.3.0 x8
10Gbps is 1.25GBps and PCI-E 3.0 x2 speed is 1.97GB/s
So x4 is enough to transmit and receive with 1.3GB/s

Some motherboards supports PCI-E bifurcation to split slots to connect more devices
 
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Aichon

Average Stuffer
Oct 16, 2017
85
232
So, if we take what you're saying about needing three slots at face value, you'll likely need an ATX board. mATX boards only have two standard PCIe slots, mITX boards only have one, and smaller boards usually have none, meaning that none of the SFF form factors line up well with what you've said you needed.

That said, there are ways to make things happen. As Vlad suggested, several boards support PCIe bifurcation, allowing you to use a sort of breakout cable to turn a single x16 slot into two x8 slots. Similarly, the M.2 slot on most newer boards can be co-opted for use as a PCIe x4 slot via an adapter, giving you the possibility of a total of three PCIe slots on an mITX board: two at x8 and one at x4. Because Vlad is also correct about the needs of 10Gbps Ethernet, you could theoretically make an mITX build with two 1080ti on a single bifurcated x16 slot and a 10Gbps NIC connected via the M.2 slot.

At that point, at least with an mITX board, you'd be entirely out of slots so you wouldn't be able to do the U.2 drive, though some high-end Intel boards have Thunderbolt 3 support baked in, and most also have at least 4x SATA 3.0 ports, so you'd be able to hit the rest of your requirements. Alternatively, if you went with mATX, which has one more PCIe slot than mITX, you'd still have a slot left, so you could put the U.2 drive in it (or else swap the U.2 out for an M.2 and then put the NIC in the empty PCIe card slot).

Unfortunately, all of this stuff is well beyond my depth, so I'll leave any further discussion for those more knowledgeable. The only other thing I might suggest is that you take stock of your needs, since going SFF is all about prioritizing. If you want something smaller, you usually need to give up some other things.
 

IntoxicatedPuma

Customizer of Titles
SFFn Staff
Feb 26, 2016
992
1,272
I think the Asrock X399M would be the only mATX board to meet his needs, but it would also need a case with 5 PCI slots to do that. That kind of limits to only some Micro ATX cases(Cerberus would work!).
 
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Jdkell3

Minimal Tinkerer
Original poster
Aug 1, 2018
3
0
So, you're all right. Some ASUS mATX boards will support bifurcation which would theoretically let me put the two graphics cards on one 3x16, and put a thunderbolt and 10GbE on the other. I've also found an Intel cord that will go from M.2 to U.2. So I think the problem then becomes what case will fit all of that.
Have any of you used an external power supply? That would free up space for fans if I take up the same amount of space as a 1U PSU and milled out the top of the case.