PCIe to MXM - A new challenger appears!

PlayfulPhoenix

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Without identifying anyone, I can relay that I have heard independently from other sources that nVidia will be supporting consumer GPUs up to at least the RTX 2080, in the MXM format. I don't know how long that support will last, if it will continue in subsequent generations, etc. But those GPUs will be available in MXM to those that hunt around, at least in the near term. This is in striking contrast to what I had heard throughout last year, which was unanimous in saying that nVidia was permanently phasing out MXM for all consumer-grade cards.

To elaborate on this a bit: nVidia has consistently felt uneasy about MXM consumer GPUs, since these compete against board partners as well as (more recently) their own reference designs. They also compromise on the control they have over how the GPUs are implemented, particularly from a cooling and performance context. Finally, their use is pretty uncommon, and thus the sales volume of these cards is quite low. Given all this, nVidia has historically elected to charge a massive premium on these cards to make it worth their while, as well as to counteract some of the negative externalities of MXM support while still providing the format to whoever really wants it.

(To be clear, on the professional side nVidia has steadfastly supported Quadro on MXM for some time, and at reasonable pricing. All indications point to this continuing for the foreseeable future.)

I am relieved that current-gen nVidia cards will land on MXM, because these GPUs are dramatically more space efficient than PCIe cards are. They also provide an opportunity to simplify system cooling solutions, perhaps down to a unified cooler (air or liquid) for the CPU and GPU in some contexts. <5L designs with top-tier GPUs and CPUs all but require this format to be possible; if I had unlimited time and resources, I'd most definitely make a build utilizing MXM to get the absolute best performance density I could. That said, the way nVidia supplies and charges for MXM cards – and the uncertainty around support – means that end users have to eat a huge price premium while simultaneously assuming that there won't be an upgrade path. It's really a shame.
 

cleveland

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Sep 8, 2016
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I dream one day get to see a "sandwich" motherboard. One side for the MXM GPU, the other one for the CPU and a hell of a well built mobo in between, to withstand the heat output.
 
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kotproger

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Jul 9, 2016
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Here you write that the MXM format is dead. But what alternatives have been proposed? At least as a concept.
And about the board in the title ... It is strange that only one line was spread. As far as familiar with the production of boards, it would not have affected the price if it were expanded to PCIE x4 or x8
 

Valantar

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Jan 20, 2018
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I was watching a Linus Tech video where he was working on an upgradable Alienware computer. In it, he implied that Alienware needed to create their own cut-down 2080 because MXM was no longer going to be supported as a form factor according to Dell. Does anyone know if that might be true? This project seems too good to pass up.
Think you misheard what was said in that video - I interpreted it simply as "MXM is too restrictive in terms of mounting", particularly the connector itself. IIRC that Alienware/Dell card uses a small flex cable for PCIe. Allows for more flexible mounting and doesn't require a connector that builds significantly up/down from the motherboard.
 
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gjarkko

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Jun 18, 2019
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Wanted to share this fun little thing I found on Alibaba, then Ebay with some keyword cross-searching.

https://www.ebay.com/itm/New-PCI-E-to-MXM-3-0-Graphics-Expansion-Card-75W-MAX-for-Mining-ETH-ZEC-ETC/323266307084?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

It's a standard MXM 3 to PCIe 1x adapter. Should be fast enough for most midrange (75W MAX! Haha) cards over the kinda short interface, and may be especially handy for those adapting to m.2 or installing it on a PCIe extender anyways.
What happened with your adapter adventures? Did you ever manage to make it work?
 

thewizzard1

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@gjarkko Only one AMD card, and only briefly. Not sure what the problem is / was, but the cards won't be recognized in Windows, and won't output from the mini-HDMI connector, either. I tested with about a half dozen older Radeon and GeForce type-A cards, no type-B.
 

Aerith

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Jan 31, 2020
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Hello, at the beggining I'd sorry for resurrecting this thread, but... Well, from what to start :D This 'thing' which author of thopic found will NOT work with 99% of MXM cards we know or not :) Let me explain why and HOW we can make it possible to use MXM cards on common PCIe mobo slots :)

1st of all, offered by whole chinesse market adapters are using x1 PCIe slot, which wont support devices that are more than 10W hungry on power, will not work. That's why i said 99% of MXM GPU cards will not work.
The power consumption, or power 'hunger' is mainly determinated by occupy of 'presence' pins of PCIe, the more you will have active the more power PCH will put into you device, up to maximum of 75W, which means that you can't run the 1070/1080/2070/2080 on this w/o external power supply :) (heard about some Radeon RX running at 80+W from PCIe, but I wouldn't risk a burn of mobo such shitty cards :D)

@thewizzard1 forget about using SMBUS/JTAG pins, they're useless for out needs. This interface is used by GPU (meaning whole card) only for vBIOS updates/chamges)

Atm I'm at the step of projecting the pcb (cheaper one than offered by EuroCOM), connection between MXM and PCIe is simple, for cards with TDP up to 75W. For cards with TDP higher than 75W I'll add and DC-DC based on well known 3-phase DC-DC from GTX/GTS 450/550/550Ti suitable to deliver up to 200W w/o extra cooling for MOSfets and chokes :)

@thewizzard1 You said you've checked "a half dozen older Radeon and GeForce type-A cards, no type-B. ", it doesn't matter if they'e type-A or B, there's only a difference in dimensions and sometimes in TDP, and as long as you can run them with a TDP below 10W they MAY work)
 
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kotproger

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Jul 9, 2016
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1st of all, offered by whole chinesse market adapters are using x1 PCIe slot, which wont support devices that are more than 10W hungry on power, will not work. That's why i said 99% of MXM GPU cards will not work.
I'm sorry, but it all sounds crazy.
Yes, I’ve tasted the described differences in the power of PCI-E connectors from x1 to x16. But this is not a power limit, but a limitation recommendation. Examine their pinouts - they all have the same number of power supply leads. And they all sit on the same power bus, which is 12v that 3.3v. The only difference is the set of data lines.

Therefore, talking about 99% in this case, even as it is indecent.
PS
At the dawn of mining, such x1 risers with various cards were actively used, and everything worked!

 
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thewizzard1

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@Aerith If you are spinning your own board, make sure to make a 2-GPU version, with Sager MXM spec (extra 3.3V and one or two other pins) :D Of the ones I recall, I I know I tried a Nvidia 210, and an AMD 5450 from an HP - Neither worked at all, the system would not see the card (booting with iGPU enabled). I stated Type A to mention they were all the smaller, lower-power variety.
 

Aerith

Minimal Tinkerer
Jan 31, 2020
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@kotproger Okay, I agree, I didn't describe my way of thinking to well ;) Every mining riser like the one from the photo you attached (and also that board which is a point of this thread) is designed to be used on mobo dedicated for mining, which have additional connectors for powering the PCIe slots directly from PSU. Also the risers 'linked' to PCIe slots via 'USB' cable have an additional power connectors on the board with PCIe x16 slot.

@thewizzard1 Both of cards you mentioned exceed the 10W power limit of the PCIe x1 slot :) g210M draws 14W, AMD 5450 11W (this one may have a chance to work :p)
 
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thewizzard1

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@Aerith Ah, the AMD one is the only one I had limited success with - It showed up in Devmgmt briefly!
Maybe I need to inject power into the MXM card with maybe a SATA connector, for 3.3/5/12V.

What card do you recommend that is inside the 10W envelope?
 

Aerith

Minimal Tinkerer
Jan 31, 2020
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@kotproger Okay, I agree, I didn't describe my way of thinking to well ;) Amount of power supply leads have nothing to do with power consumption of a card placed in PCIe slot, almost every PCIe card uses all pinouts, but that doesn't mean they draw full power from PCIe slot. As I said, maximum power that's delivered to a card is determinated by occupy of "PRESENCE" pins of PCIe slot, by activating these pins you "let know" mobo (PCH) what type of card is placed in slot (x1, x4, x8, x16) and PCH decide how much power can be taken from PCIe.

Every mining riser like the one from the photo you attached (and also that board which is a point of this thread) is designed to be used with mining dedicated mobo (f.e H110 PRO BTC+) which have additional power connector (mainly a MOLEX connector or SATA connector) on the board to power the PCIe slots directly from the PSU. This is a trick that allow you to cheat the PCH power limits for PCIe x1 and use a full x16 cards in x1 slots w/o power limitations.



It can be clearly seen on risers that uses combination of PCIe x1 insert 'card', USB 3.0 cable as a link (double differential pair) and a board with PCIe x16 slot and power connector/management circuit. No power is taken from mobo/x1 slot via the USB cable, all power you deliver to the GPU is taken directly from PSU via connector on riser board.


This type of riser can be used with any mobo since it has it's own power supply (no need on extra power connectors for PCIe on mobo) :)

Edit: sorry for duplicating the 1st part of reply, something went wrong :D

@thewizzard1 ATI Mobility Radeon HD 3410 (7W power requirement, MXM-II interface type, compatible with MXM3 slot) is the only one with power requirement below 10W. At 10W there are few cards: ATI Mobility Radeon HD 530v (MXM-A 3.0), Nvidia Quadro NVS 120M (MXM-III), Nvidia Quadro NVS 150M (MXM-I, not confirmed).
Or just simply get one riser like the one from 2nd photo i shared, it costs 3-5USD, so it's fine for test purposes :) For normal operation it's a misunderstanding using riser for a riser :D while MXM standard is designed to be compact :D
 
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Aerith

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Jan 31, 2020
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Design update 1: I gave up a project of PCB for a while, at 1st tried to make a prototype of a prototype ;) (before wasting time on designing a PCB that wouldn't work at all) and I'm surprised - it worked :D Ofc have whole lot of interferances and image distorions, but I expected that, can't expect a lot from wire-to-bareboard connections. Test conditions: Nvidia Quadro K3100M (MXM 3.0 type B, 75W TDP), tested with x1, x4, x8, x16 link connection (all 'PRESENCE' pins connected/present during any link width test), no external power applied, SMBUS/JTAG pins not used, test made with HDMI output (didn't try DP/eDP, LVDS. Also didn't try VGA interface since it requires external DAC cicruit on which I didn't want to waste a time). Tried to run test with only one 'PRESENCE' pin connected, but windows didn't recognize the card within any condition.
Test platform: Asrock Z77 Extreme 3, E3-1270v2, 16GB DDR3 1600 (4x4)

Now it's time for serious projecting :D
 
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ExplodingWaffle101

SFF Lingo Aficionado
May 11, 2018
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Design update 1: I gave up a project of PCB for a while, at 1st tried to make a prototype of a prototype ;) (before wasting time on designing a PCB that wouldn't work at all) and I'm surprised - it worked :D Ofc have whole lot of interferances and image distorions, but I expected that, can't expect a lot from wire-to-bareboard connections. Test conditions: Nvidia Quadro K3100M (MXM 3.0 type B, 75W TDP), tested with x1, x4, x8, x16 link connection (all 'PRESENCE' pins connected/present during any link width test), no external power applied, SMBUS/JTAG pins not used, test made with HDMI output (didn't try DP/eDP, LVDS. Also didn't try VGA interface since it requires external DAC cicruit on which I didn't want to waste a time). Tried to run test with only one 'PRESENCE' pin connected, but windows didn't recognize the card within any condition.
Test platform: Asrock Z77 Extreme 3, E3-1270v2, 16GB DDR3 1600 (4x4)

Now it's time for serious projecting :D
pics? :p
 

kotproger

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Jul 9, 2016
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Okay, I agree, I didn't describe my way of thinking to well ;) Amount of power supply leads have nothing to do with power consumption of a card placed in PCIe slot, almost every PCIe card uses all pinouts, but that doesn't mean they draw full power from PCIe slot. As I said, maximum power that's delivered to a card is determinated by occupy of "PRESENCE" pins of PCIe slot, by activating these pins you "let know" mobo (PCH) what type of card is placed in slot (x1, x4, x8, x16) and PCH decide how much power can be taken from PCIe.

Every mining riser like the one from the photo you attached (and also that board which is a point of this thread) is designed to be used with mining dedicated mobo (f.e H110 PRO BTC+) which have additional power connector (mainly a MOLEX connector or SATA connector) on the board to power the PCIe slots directly from the PSU. This is a trick that allow you to cheat the PCH power limits for PCIe x1 and use a full x16 cards in x1 slots w/o power limitations.
You are not quite right. Such motherboards have additional power inputs only because of the large number of video cards connected to them. If 1-2 are connected, then a 24-pin 12V contact connected through 24 is enough to provide 75 watts per slot. even if device x1 is inserted. For example, video cards through the riser I provided in the last post are connected physically as x1 devices and get enough power, which indicates that there are no direct power limitations depending on the format of the slot.
There is only an agreed maximum limit of 75 watts of total power from the slot.

Again, the risers that you showed are not intended to deceive a nonexistent restriction for one slot, but allow you to avoid cumulative overload on the system with multiple connection of video cards, because standard motherboards are not designed for this scenario.

Well, or maybe I misunderstood your answer)