GPU Thin Mini-ITX with discrete graphics card

Ceros_X

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Mar 8, 2016
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So, a lot of people have asked about using a discrete graphics card in a thin mini-itx board, but the problem is always the 25W provided by the 4x PCI-E slot being insufficient to run the card. Has anyone ever tried a powered PCI-e 4x to 16x riser cable? Something like this ? Provided it was a shielded cable like the Li-heat ones, should this be sufficent to work? I know bitcoin miners have been running full power graphics cards off of 1x slots for a while using this but don't know if it has been looked at from a uSFF point of view.

Ideally someone would make one that would allow the 16x orientation to be reversed (to allow for the CPU fan and the graphics card fans to face the same direction) but that's probably pushing it... QinX, iFreilicht lol?
 
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Ceros_X

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Mar 8, 2016
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I was of the assumption that a powered (PCIe x/8 pin) GPU doesn't draw power from the PCIe slot - maybe thats an alternate way around this?

According to what I was reading here, that's not the case? I also believe QinX mentions it in his build log but he seems to want to cut power to the slot entirely vs supplementing it (I was always a bit hazy about that voodoo part reading through his build).
 

QinX

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Mar 2, 2015
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I've found that you can run the GPU and have it also use the 12V from the PCIe slot, but because a GPU in general is configured for a 75W PCIe slot I went with the solution to completely cut the 12V supply from the PCIe slot.
Some GPUs use the PCIe slot for power, the new ASUS GTX950 takes 75W from the slot, so that would be an example of a card that might not work with a PCIe 4x slot on a Thin-ITX board because the standard says, only a 16x slot may provide 75W of power.

My solution and the reason I had chosen it is to make sure any GPU that is within the power budget and size constraint can be used regardless of the power it needs/wants from the PCIe slot.

edit:
Also that Powered riser you linked should work just fine, it is basically the exact solution I had used, only I had made a single PCB powered riser not a flexible powered riser
 
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QinX

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kees
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That's what I'm researching with KogelMier.
I'm looking for a way to not need a true DC-DC board like the HD-Plex, but a straight-up On-Off switch PCB that is minimal in size and cost.
I think I have found it, but I've not taken/found the time to disassemble my system and try the new solution.
 

EdZ

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May 11, 2015
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Tomshardware's test of the 980ti (among other) measures the power draw from the motherboard as about 55W on average, peaking to 70W, so even cards with external power still draw power from the motherboard. I suppose it's possible that PCIe card manufacturers would add in logic that if power from the motherboard is cut that the PCIe power connectors will 'take up the slack', but as that's well outside what the PCIe standard says should happen it's more likely that a failure to detect motherboard power will just result in the card not powering up at all.
There's also the nonzero 3.3V power draw, so even if the 12V traces from the motherboard were cut and a supplemental 12V supply connected, you would either need to keep the 3.3V traces connected, or supplement those as well.
 

QinX

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kees
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There's also the nonzero 3.3V power draw, so even if the 12V traces from the motherboard were cut and a supplemental 12V supply connected, you would either need to keep the 3.3V traces connected, or supplement those as well.

That is true, but isn't as relevant, the power allowance for 5V and 3.3V is the same across all PCIe slot sizes. Only the PCIe 16x slot has a High Performance Mode that allows 75W powerdraw. That is the reason you only see external 12V Molex connectors for risers and PCIe PEG sockets on motherboards that support a large amount of GPU's, 12V is the major limiting factor.
 
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iFreilicht

FlexATX Authority
Feb 28, 2015
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I've tested a GTX970 on a thin mITX board and that worked out completely fine, it seems like that just drew most of its power through the PEG connectors.
For safety reasons, I would either cut all 12V power connections from the PCIe slot to not overload the Mainboards VRMs, or use a powered riser, like QinX did. The one you link seems absolutely fine, too, though you might get EMI problems with it.
 

aquelito

King of Cable Management
Piccolo PC
Feb 16, 2016
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Hi there,

My current project is to fit a GTX 970 watercooled by a dual 92mm AIO kit (Asetek 565LX) into a Streacom F7C. CPU is an i3 6100.

It fits but bearly, and using a H110 thin-itx board would help a great deal.



I am currently using a 3M x16 riser ; given the space constraints, this is the only one flexible enough to work with my case.

Is there a risk for my mobo if I keep my 3M riser, and power the GTX 970 with my HDPLEX 250W ?
What would be the best solution ?

Other point : the 4Pin 12V connector available on the board can replace the on-board 19V DC-IN.
Is it a safer option to provide power to the mobo with the HDPLEX 250W (which 24Pin connector being jumped)?
 
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QinX

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You shouldn't see any problems using powering the GTX970 via both the PCIe slot and the HDPlex.

The best solution in my opinion would be what I did, supply all 12V via the HDPlex, but that would mean modding the 3M riser.

What a strange thing they have done with the 12V EPS connector and the input range.
It used to be 12V to 24V on the DC jack and the internal 2pin connector.
Now it seems to be 19V to 24V on the external DC jack and 12V only on the internal 4Pin?

Edit:
A quick browse through the manual reveals that it can still output the DC voltage, so it seems it can still be used as a passthrough, so it can be used to power the HDPlex.
However as an input it can only do 12V. Perhaps it circumvents or is after the 12V stepdown converter?

Here's the manual, look on page 13
http://download.gigabyte.ru/manual/mb_manual_100tn(gsm)_e.pdf
 
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aquelito

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Feb 16, 2016
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Thanks a lot Qinx !

Is there any "soft" modding possible (like masking the 12V line) ? I do not feel comfortable modding this 80 € riser !

I noticed that point in the manual but I do not think I understand everything...
Can I use the HDPLEX to power the CPU through that 12V EPS connector ? In other therms, what is made for ?

Indeed, Gigabyte does not specify what power the on-board DC-IN can handle. I remember the Asrock H81 thin ITX being compatible with up to 150W bricks.

EDIT : Asrock also have its H110 thin ITX mobo, which has the 2Pin connector you're mentioning .

Here is a list of power bricks (from the manual) :

DELTA DELTA-ADP-150TB-150W/19V
HP HP-TBC-BA52-150W/19V
FSP FSP-FSP150-ABAN1-150W/19V
DELL FA130PE1-00-130W/19.5V DELL
LA90PE0-01-90W/19.5V

Which one would you choose ?
 
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QinX

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Are you asking for motherboard advice or for the AC-DC Adapter?

For the motherboard. I'm more of a Gigabyte fan, but they've changed some stuff on the H110TN that I don't like, mostly with the input.
I've also noticed the DC input jack on the Gigabyte board has been changed to a smaller version, the dimensions escape me. But a Dell or Voodoo brick won't work with that DC jack.

If I were to buy one of these boards I'd go with the Asrock. Better layout and compatibility, sticks to Thin ITX guidelines more. The only downsides I can see for it would be no wide-input voltage and only 2 USB3.0 on the back, although you can get 2 more via the internal header.

For the DC Adapter, I'd try and stick to 1 DC adapter for the motherboard and GPU. So go with a Voodoo or a Dell 330W.
 

iFreilicht

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Feb 28, 2015
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12V to 24V on the DC jack and the internal 2pin connector.

Official spec was 12-19V for the 1151 boards, pretty sure about that. It was never mentioned in the manual, though.

I've also noticed the DC input jack on the Gigabyte board has been changed to a smaller version

That is far beyond stupid, why the hell would they do that?

It doesn't say whether the power output from the 4-pin connector is regulated or not. The only way to know for sure is to get one and measure it through.
 

aquelito

King of Cable Management
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Feb 16, 2016
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Thanks to both of you.

So, to sum things up, the following setup seems correct to you (from your topic on [H] forums) ?



- What is the Add2PSU unit intended for ? Could you just jump the 24Pin connector on the HDPLEX ? My goal is also to get rid of the 24pin cable.
- Is it mandatory to cut the 12V lines on the riser ?
 

QinX

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kees
Mar 2, 2015
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Almost correct but not quite, the 2-pin tot 4-pin cable from the motherboard to the HDPlex needs to be moved. On the HDPlex it's the connector on the center left.

You don't need to cut the 12V lines.

You can't jumper the 24-Pin, that would cause the HDPlex to always be on and with it the GPU would always have 12V applied, this messes up the boot sequence.
Getting rid of the ADD2PSU is possible but you will have to solder your own jumper.

Something like this:
So instead of just 1 wire you have a MOSFET between it and use the sata connector to apply 5V on the GATE. this turns on the MOSFET which jumpers the PS_ON and GND and the HDPlex starts. This has always worked for me. Do not use the 12V, in my experience it is slower to rise and can cause the system to not wake from sleep, at least that is what happened to my system. the 5V line is quicker to rise.

 
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aquelito

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great ! Thanks Qinx. Yes indeed, I mixed up the SATA and 19V DC-IN ports...

EDIT : Just stumbled on this HDPLEX 160W DC-ATX converter :



A 160W unit is to be released next month. Could it be used to power a whole thin-itx system with a GTX 970 by itself ?
Any risk it might damage the mobo ?
 
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CC Ricers

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Nov 1, 2015
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So I'm gonna bump up this topic because this has started to interest me as well. I'm thinking how can a setup with a 75W card work. With a 75W card that has no additional PEG connectors you have less connections to manage, but you still need to provide external power where the PCIe 4x slot couldn't provide.

I found this connector which I have one of I believe for bitcoin mining. Data goes through USB and power comes from a Molex connector which they provide an adapter cable to SATA. I don't really know if using SATA power directly from the motherboard's power header is a good idea, though.
 

robbee

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Sep 24, 2016
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That's an interesting connector you got there. I'm very interested if anyone has any experience with something like that. Especially what concequences there are connecting a gpu to a x1 slot.