[aberrero]

Interesting.

I did some googling to see if any motherboards supported bifurcation, but couldn't find anything. One guy who asked in the MSI forums got his topic locked because "this would only be used for bitcoin mining or other shady activities that are not supported"

 

[CynicalUnicorn]

Quote:

Originally Posted by aberrero

Interesting.

I did some googling to see if any motherboards supported bifurcation, but couldn't find anything. One guy who asked in the MSI forums got his topic locked because "this would only be used for bitcoin mining or other shady activities that are not supported"

Yes, because wanting/needing GPUs for number crunching must be Bitcoin. No other explanation.

Is anybody clear on how those work? I assume it's a PLX switch, like what's in the 64-lane ASRock and ASUS X#9 boards. They don't have 64 lanes of bandwidth - just the stock 40 - but the devices can actively share them as opposed to the passive "these two slots share lanes upon booting up" you see on most SLI and crossfire capable Z#7 boards.

Quote:

Originally Posted by Aibohphobia

You're right, I posted the wrong one. I edited my post with a link to the splitter: http://www.ameri-rack.com/ARC2-PELY423-C7_m.html

Not sure how well that would work in practice. Remember, it has to plug into an initial x16 slot, and both split slots can't be used unless the case has three expansion slots. At that point, you should look into mATX.

 

[veryrarium]

I'm totally ignorant, is it the case that a motherboard needs this "PCIE bifurcation" support for any PCIE splitter (from any number of lanes, not just x16) to work properly on it?

I have this MSI miniITX board that has a PCI slot, a PCIe x1 slot, and a mini-PCIe slot (actually, even a CF slot on the flipside), with the PCI and the PCIe x1 positioned "in series" (instead of side by side vertically as in mini-DTX) at the bottom, and I have been wishing for motherboard manufactures to now put two PCIe 3.0 x8 slots in series on a mini ITX. But I guess by extending the board size to miniDTX there's not much chassis compatibility lost as the OP mentions.

 

[Aibohphobia]

Quote:

Originally Posted by CynicalUnicorn

Is anybody clear on how those work? I assume it's a PLX switch, like what's in the 64-lane ASRock and ASUS X#9 boards. They don't have 64 lanes of bandwidth - just the stock 40 - but the devices can actively share them as opposed to the passive "these two slots share lanes upon booting up" you see on most SLI and crossfire capable Z#7 boards.

I was looking through the Intel socket 2011-v3 documentation while trying to settle a debate about the lane configuration on the EVGA X99 Micro and it uses the term bifurcation when talking about splitting a x16 slot into two x8 slots using the lanes off the CPU itself. So it doesn't just apply to PLX switches.
Quote:

Originally Posted by CynicalUnicorn

Not sure how well that would work in practice. Remember, it has to plug into an initial x16 slot, and both split slots can't be used unless the case has three expansion slots. At that point, you should look into mATX.

It's not very practical for standard cases but it could make for a very cool Steambox type build.

 

[fleetfeather]

Quote:

Originally Posted by CynicalUnicorn

Excuse me?! SODIMMs, sir! Look at your laptop. Two SODIMMs in a line would be maybe 10% longer than a single DIMM. The only "issue" is that the frequency is much lower than desktop RAM.

You do realize that mATX is a very broad standard, right? It's simply using a certain placement of standoffs and must be between 171mm and 244mm in both dimensions. That means up to the four-slot, four-DIMM square we all know and love all the way down to something negligibly larger than mITX.

There are mATX boards that fit the mDTX standard (almost) exactly, but are labeled mATX. ECS has some, H61 and H81 I believe.

mDTX itself is just mITX plus an extra 33mm of height. Widen it to a 203mm square, and it ought to fit in most mITX cases while maintaining quad-channel and dual x16 slots.

I don't have a problem with the SODIMM arrangement you're quoting; I didn't realise end to end pairs were only slightly longer than a full length DIMM

Yep, I'm aware of the standards for each board type and what they're dependent on, but I don't really feel that's the point here.

I mention mITX and mATX in their stereotypical sense; the way in which we all immediately associate the form factor being.

Regardless of the flexibility of the standard/s, the point is trying to communicate what size board and what board features that we want

 

[InfraRedRabbit]

the NCASE M1 is the perfect case to take advantage of this!

it has 3 pcie slots so the ability to mount a single slot pcie (audio/SSD) and still maintain a 2 slot GPU.

man i would jump for this in an instant over mITX - opens the doors to far more options if only motherboard and case designers would see the possibilities.

really it would take a big company like ASUS (who already make motherboards, and some custom cases i think?) to jump on the bandwagon to see this take off.

can dream though

 

[aberrero]

Quote:

Originally Posted by InfraRedRabbit

a single slot pcie (audio/SSD)

The Asus Impact motherboard already kind of deals with this, by having upgraded audio in a daughterboard as well as a fast m.2 slot. I think that is much more practical than having a dedicated sound card in an mITX build, and Asus's sound card is pretty good from what I understand.

I really just want to see a DTX build with dual 295X2 cards, 32GB ram, and 8-core Haswell-E. It would fit in something the size of a Corsair 250D, and it would be amazing. As fast as any computer anybody can build today.

 

[InfraRedRabbit]

Quote:

Originally Posted by aberrero

The Asus Impact motherboard already kind of deals with this, by having upgraded audio in a daughterboard as well as a fast m.2 slot. I think that is much more practical than having a dedicated sound card in an mITX build, and Asus's sound card is pretty good from what I understand.

I really just want to see a DTX build with dual 295X2 cards, 32GB ram, and 8-core Haswell-E. It would fit in something the size of a Corsair 250D, and it would be amazing. As fast as any computer anybody can build today.

the impact is also 350AUD, which makes it a pretty massive turn off - given if dtx was an option i could buy a Z97 dtx board for maybe 150AUD

for more that matter the HTPC user who wants to install a GPU/sound card - they only need a 60AUD H81 board.

the impact makes sense where it doesnt cost the world and for those that game. anyone else gets no benefit from it.

DTX could benefit a wehole not more people than the niche market you describe.

 

[fleetfeather]

Quote:

Originally Posted by InfraRedRabbit

the impact is also 350AUD, which makes it a pretty massive turn off - given if dtx was an option i could buy a Z97 dtx board for maybe 150AUD

for more that matter the HTPC user who wants to install a GPU/sound card - they only need a 60AUD H81 board.

the impact makes sense where it doesnt cost the world and for those that game. anyone else gets no benefit from it.

DTX could benefit a wehole not more people than the niche market you describe.

Well, whatever the 150 AUD Z97 DTX is, you can guarantee the componentry and connectivity is going to be crap. Despite it's high price point, the Impact actually justifies its price.

 

[InfraRedRabbit]

Quote:

Originally Posted by fleetfeather

Well, whatever the 150 AUD Z97 DTX is, you can guarantee the componentry and connectivity is going to be crap. Despite it's high price point, the Impact actually justifies its price.

i payed 170AUD for my ASUS Z87I-Pro and thats pretty reasonable quality. theres a point of diminishing returns on motherboards (in AUD at least) at about 170-180AUD

im just saying think about the mini-DTX form factor in a broader context than just in what you want for your high spec SLI/CF monster

 

[aberrero]

Don't worry. I can't afford it either.

But it can be useful for two water cooked midrange cards

 

[NFSxperts]

Quote:

Originally Posted by Dyson Poindexter

I think it is time we make a push for some of the big names to develop proper Mini-DTX motherboards for today's processors and chipsets. SFF enthusiast computing continues to enjoy mainstream popularity, with all the major players having enthusiast ITX boards. I believe Mini-DTX is a natural progression, and a technical no-brainer for the likes of EVGA, Asus, MSI, Gigabyte, Asrock and others.

I'd like to open this up as a discussion among all of us in the SFF community, and show the motherboard vendors that demand exists for these boards. There might be a trademark issue with using the name "Mini-DTX," in which case I'd call it "Extended ITX" or "ITX Plus." Some are just sold as mATX boards even though they only have two slots. Regardless, I think there are nothing but advantages to moving to this form factor. Motherboard vendors will enjoy the increase in board space for routing and placing components. Case manufacturers have nothing to change except the words on the box, stating support for Mini-DTX. (and many already list it) We, the enthusiasts and end users gain extra versatility without sacrificing case selection or desk space.

Good idea on starting this thread. There were several builds where I wished had two pcie expansion slots. I think we should push for this form factor.
(gpu+sound card for htpc), (sata exapnder or raid card+intel nic for file server)
You have good points about case compatibility, which is why I agree completely with what you said.

For the guy who suggested a wider dtx form factor, I think only a few existing m-itx cases will be able to support it.

Quote:

Originally Posted by Shadow_Foxx

Put me on the list! If all itx boards moved to DTX, there would be no loss for ITX users (extra slot doesnt need to be used/fits in all existing itx cases with dual slots), but a gain for those who want pcie audio or SSDs along with a graphics card, or dual watercooled gpus.

I dont know jack about mobo design, but it seems like adding another slot shouldnt be that excessive? I could be totally wrong.

I think there needs to both m-itx and dtx. Most uSFF cases does not have any expansion slots.
Would both pcie slots be x16? or x1 and x16? Which would be on the top? If its at the bottom, then existing case compatibility would be lost for dual slot gpu.
Better yet, they should come up with an attachment similar to risers which could "extend" the m-itx formfactor to dtx. split the x16 lane to 2 x8 slots.

Quote:

Originally Posted by Insan1tyOne

I second this! Don't get me wrong, I love my Rampage IV Gene and 350D but I just want to move down to something smaller and still retain all of the enthusiast qualities that my RIVG has!

The point is, is that you could have a pretty small case (lets say the new Phanteks Enthoo Evolv) that supports a TON of watercooling and other options but only supports m-ITX boards. That is why m-DTX would be great.

Am I looking at the wrong case? The evolv I'm looking at is matx at around 40L

 

[fleetfeather]

mITX cases capable of supporting a widened mDTX mobo:

CM Elite 110
CM Elite 130
Corsair 250D
EVGA Hadron Air (with HDD cage removed)
EVGA Hadron Hydro (with HDD cage removed)
Silverstone SG05
Silverstone SG08

These just off the top of my head. I'm sure could go on, but I really don't feel like trawling website catalogues. Any case which supports GPU's longer than 170mm and doesn't have a structure (like a HDD cage, or PSU) right next to the edge of the mobo will support widened mDTX mobos....

 

[Dyson Poindexter]

Quote:

Originally Posted by CynicalUnicorn

Is anybody clear on how those work? I assume it's a PLX switch

Well, the 115x Intel chips can do this natively, as we all know the x16 slot can turn into two x8 slots. (unless a PLX bridge is used, which isn't always the case) This "bifurcation" card likely just takes the front and back halves of the x16 slots and brings them out to two electrical x8 slots. The Intel chip is obviously capable of this, but I imagine there are some requirements as far as telling the chip what is going on.

A standalone PLX-routed board does exist, but is quite expensive: (in the hundreds)



Regardless, externally splitting the lanes isn't a very forward-looking solution.

Quote:

Originally Posted by aberrero

I've been thinking that we need this for a while.

Quote:

Originally Posted by InfraRedRabbit

the NCASE M1 is the perfect case to take advantage of this!

it has 3 pcie slots so the ability to mount a single slot pcie (audio/SSD) and still maintain a 2 slot GPU.

man i would jump for this in an instant over mITX - opens the doors to far more options if only motherboard and case designers would see the possibilities.

Quote:

Originally Posted by NFSxperts

Good idea on starting this thread. There were several builds where I wished had two pcie expansion slots. I think we should push for this form factor.
(gpu+sound card for htpc), (sata exapnder or raid card+intel nic for file server)
You have good points about case compatibility, which is why I agree completely with what you said.

Thanks for the feedback so far! I think we can all agree that even if your application doesn't require both slots, having the option isn't going to hurt anyone. It's a "nothing to lose, everything to gain" situation. There are a couple ITX cases that do have 3 expansion slots, like the NCASE M1, which would allow for some flexibility in using a two-slot GPU in the second slot.
Quote:

Originally Posted by fleetfeather

mITX cases capable of supporting a widened mDTX mobo:

CM Elite 110
CM Elite 130
Corsair 250D
EVGA Hadron Air (with HDD cage removed)
EVGA Hadron Hydro (with HDD cage removed)
Silverstone SG05
Silverstone SG08

Awesome list! I can think of the HAF Stacker 915 series as well, and tons more with simple mods. Nearly all "shoebox" cases could be made to fit.

 

[CynicalUnicorn]

Fleetfeather: you are right, we generally think of mATX as a 244x244mm square. However, of the four mATX boards in my possession, just one is the full sized form-factor. One is basically mITX with three expansion slots. None of the three "non-standard" boards are the same size either.

Thanks for the list of cases too. I quite like the look of the Hadron Air myself. Would be a nice case for an mITX build, and knowing it supports DTX is a plus.

Dyson: yeah, you're right, Intel chips can do that. But I'm not sure how much of that is the CPU's doing. That feature is limited to the Z boards only, implying the chipset is partially responsible. Of course, it could just be an arbitrary limitation. I honestly do not know.

 

[Dyson Poindexter]

Quote:

Originally Posted by CynicalUnicorn

Fleetfeather: you are right, we generally think of mATX as a 244x244mm square. However, of the four mATX boards in my possession, just one is the full sized form-factor. One is basically mITX with three expansion slots. None of the three "non-standard" boards are the same size either.

Thanks for the list of cases too. I quite like the look of the Hadron Air myself. Would be a nice case for an mITX build, and knowing it supports DTX is a plus.

Dyson: yeah, you're right, Intel chips can do that. But I'm not sure how much of that is the CPU's doing. That feature is limited to the Z boards only, implying the chipset is partially responsible. Of course, it could just be an arbitrary limitation. I honestly do not know.

Yep, a lot of the budget mATX boards are three slot, and about as narrow as an ITX board:



There's even a few "mATX" boards that fit the Mini-DTX size, but they all use H61/H81 chipsets for whatever reason.



We just need these compact two-slot boards to inherit some of the enthusiast ITX features and then we are golden.

Regarding PCIe splitting: The PCIe lanes (ever since 1156) for the slots go directly to the CPU, so I feel it's an artificial limitation the chipset imposes. There might be a some technical reason behind it, but knowing Intel it's probably just bracketing the market.

 

[CynicalUnicorn]

H61 and H81 are awful. They're PCIe 2.0 for no reason and support only one DIMM per channel. I guess we should be glad it's dual-channel? But that means it only supports two DIMMs and can't be a full 244mm without wasting a lot of space. No reason a better chipset can't be that size, you are correct. B85 is a good starting point and, assuming you don't need/want dual x16 slots, just as good as Q87 or H97.

The first board you linked is AM1, right? That's mine - 170mm wide, about 230mm tall. There are a few mDTX AM1 boards too, labeled mATX. That's single-channel and two DIMMs per channel, again, limiting it to less than 244mm wide. Since the chips' TDPs are 25W, there is absolutely no reason to make them larger to accomodate VRMs. The chips are SoCs too, meaning the southbridge is on-die. AM1 motherboards are only for power delivery and usable I/O; everything important is on the APU.

 

[fleetfeather]

So what features do we all want? What dimensions?

Let's ask the questions using Google Forms, then take the most popular suggestions and prototype it.

Once we have a clear prototype and a clear rationale, we can take it to the Asus / EVGA forums and put forward our case

 

[m_jones_]

Quote:

Originally Posted by fleetfeather

So what features do we all want? What dimensions?

Let's ask the questions using Google Forms, then take the most popular suggestions and prototype it.

Once we have a clear prototype and a clear rationale, we can take it to the Asus / EVGA forums and put forward our case

I'm sorry but they won't most likely even care what a niche within a niche small community has to say on this topic.

 

[Aibohphobia]

Quote:

Originally Posted by aberrero

Once we have a clear prototype and a clear rationale, we can take it to the Asus / EVGA forums and put forward our case

Probably want to talk to Gigabyte, they seem willing to do small run semi-custom boards: https://www.kickstarter.com/projects/quo/projectq-run-any-os-the-unique-motherboard

That Kickstarter seems to have run into issues but I think that's on the creators end rather than problem with Gigabyte.