My64 Mini-ITX Case and HiFive Unmatched

I ordered a HiFive Unmatched which I expect to receive sometime this year and I preemptively purchaseed an interesting mini-ITX case for it that I am pretty excited about!

Check out the My64:

I assume that the Unmatched should work fine with this. Anyone have any reason to believe it would not? I suppose if I plan to use the PCI-E expansion, I would need a riser/riser cable and mount it inside somewhere – but it does seem as if it would work.

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The one reminder I would give, is that the HiFive Unmatched does not include any video. If video is needed, then you have 2 choices;

  • PCIe card
  • USB DisplayLink

The last is simply a video card on a USB dongle. (It is NOT DisplayPort over USB-C…)

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I intend to mount the PCI-E card I end up using sideways in the chasis using something like this cable or a right angle PCI-E adapter.

I just found this crazy M.2 graphics card: THIS is a Graphics Card..?? - YouTube


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I just got my My64 Mini ITX case and it includes a keyboard as part of the case and an I/O bracket. These require USB 2 headers. I may need to use up the PCI-E slot for a card that has USB headers. Its going to be interesting attempting to get this all working…

There are other M.2 type graphics cards. For example, I ran across the following card several months ago;

Another user here also posted a link about it;

As noted elsewhere, you have to be careful with M.2 cards. The Unmatched uses M Key but these M.2 video cards may not be work in a M key only slot. Over all, the M.2 standard is quite complex and has led to many incompatibilities.

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There are also M.2 cards that are USB controllers. I wouldn’t imagine that any PCIe device wouldn’t work properly on the board, since PCIe is intended to be cross-platform, but, of course, caveat emptor; buy at your own risk. (Or if you have the skill, you can fix up the driver to make it work!)


Yes I see a few Yeston Radeon RX550 – time to experiment.


One thing that should probably be mentioned, is that many NVMe card slots are 22mm wide. Part of the M.2 size standard includes both length and width. Thus, 2242, 2260, & 2280. However, the card I linked to above, is 3060, meaning it is 30mm wide. This may prevent installation in some M.2 slots. That width could also affect other implementations, like SATA or USB M.2 cards.

I’ve not checked the SiFive Unmatched board’s M.2 NVMe slot for width. Just something to keep in mind when spec’ing out a M.2 card.


I’ve seen the following M.2 devices, at least online:

  • NVMe storage

  • SATA storage

  • Wifi/bluetooth

  • Ethernet, including dual port 1G

  • VGA video

  • USB ports

  • SATA adapter (for external device)

  • CAN bus

  • 4G LTE

  • GPS

  • SDR (Software defined radio)

  • ADC (analog/digital converter)

  • Serial RS-422/485

  • FPGA

  • NGFF Key M Adapter, PCIe3.0 X4 Adapter, Convert PCIE Device

  • NGFF NVMe Key M Extender Cable to PCIE x16 Graphics Card Riser Adapter 16x PCI-e PCI-Express

Wikipedia has a breakdown of the various mechanical interfaces:

Happy hacking!


Useful! Thank you! Seems like M.2 M key is like an extra PCI-E x4 port. Cool!


I have a FormD T1 built waiting for the board to arrive. Corsair SF450 PSU w/pslatecustom sleeved cables.

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I just thought I would show my WIP idea on getting a graphics card (Yeston rx550) into a My64 mini ITX case. everything may change all of a sudden once I get the Hifive Unmatched in the case though.

This pic shows the position in case I am thinking. I have a riser cable currently holding it up which will very likely change.

… and here is a rough idea of how it will look peering outside the case.

at the moment I may just mount the graphcs card inside on motherbord standoffs and have a 3d printed plate made where I will add panels for graphics card access.

I know this looks a bit crazy but its a little puzzle for myself that I thought I’d share.


Thanks for sharing the pictures of your WIP.
I’m also interested by the my64 mini-itx solution, but in a second time. I planned to use an old PC chassis where the mini-ITX will have plenty of space and I will see what comes up. I also planned to use an old Asus Radeon HD6450 Silent (1GB DDR3) because it has no fan, just a dissipator on top of the GPU and it’s a low profile card (only powered through PCI bus, below the maximum 75 W). It will be of course less powerful than your RX550, but I think it’s sufficient for the desktop stuff I plan to do.

About your GPU card’s choice I was wondering: the air exhaust will tap into the keyboard’s PCB right ? Then there might be some thermal dissipation issues, depending on the load put on the GPU. It will throttle in that case I guess. And the typing experience might be unpleasant if it’s getting too hot below the keyboard.

In all cases I’ll follow your experience here as I might buy this case as well.

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After I posted the pictures of the My64 with graphics card, i realized if I slotted the card inside the optical bay like that the fan would indeed be blowing right into the left half if the keyboard. I now plan to find a way to lay the card upward on the bottom of the case using possibly motherboard standoffs and I will video extension cables that will poke through a custom plate I will 3D print… However, I decided before I waste more money on ideas, I should have the Unmatched in the chasis first.

I know this case has heat dissipation issues, but this Yeston card seems to be a non-overclocked card and I read specs somewhere saying that the power draw is 40W. I’ll have to wait and see if this is true or not.

Thanks for your interest! I will update this thread once I get my Unmatched board.

UPDATE: I might go this route with a custom I/O plate for at least just VGA out:

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My AMD WX7100 GPU arrived from Newegg and I just need the motherboard now in a couple weeks. Boy GPU availability sucks right now. Had to jump on Newegg restock as otherwise sellers were doubling the price!

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I’ve been looking around for rackmount cases for the Unmatched Mini-ITX board. Here’s a list of manufacturers I found that make rackmount Mini-ITX:

  • Athena Power
  • Build-a-Blade
  • Casepro
  • Circo Technology
  • DV Industrial Computer Ltd.
  • Idiotpc
  • In Win Development
  • iStarUSA
  • nVent
  • Onlogic
  • Shenzhen Epona Tech. Ltd.
  • Silger
  • SilverStone
  • Supermicro
  • Travla


  • The manufacturers themselves, in many cases.
  • NewEgg and the other majors
  • Rackmountnet
  • Miller Technologies

In another thread, there is a discussion about the height of the heatsinks and whether they will fit in a 1U case. The consensus is “no”, it won’t fit. So either a taller case or a shorter heatsink is needed.

I have not seen the “shield” that comes with the Unmatched, if it will come with any at all. The shield is the metal plate that goes over the ethernet port, USB, etc. when you mount it in a case. Those in general do not fit in 1U cases, so they need to be cut down. Some suppliers offer that as a service. You can just hack it yourself or make one from scratch. Some case designs come with a shield grid where you just punch out for your connections.

There are 1.5U cases available, around ~57 mm tall, which should be tall enough for the motherboard + heatsinks. They are more rare.

There are a few cases that allow mounting of two motherboards in one case:

  • 1U Athena Power RM-1U100DD
  • 2U Casepro M236 (I think same as Travla)
  • 2U iStarUSA 218M2
  • 1U Travla T1200
  • 2U Travla T2240

There is a high density solution for Mini-ITX boards that pack 9 motherboards into 6U such as the Build-a-blade BB-ITX96 V2. I don’t know if the Unmatched would work in there though. I’ve seen some solutions that replace the heatsink with low profile heat pumps, but those are mostly for larger Intel processors (haven’t seen a 22mm one). DV Industrial Computer Ltd. makes (made?) high density solutions for Mini-ITX as well.

Other notable rackmount cases I came across:

  • 1U iStarUSA D-118V2-ITX-WB, pretty wood panel. :slight_smile:
  • 1.5U Onlogic MK100
  • Supermicro has their “super chassis” line
  • Various models offer front panel I/O option
  • Silger CXR-1200 case designed to support PCI bifurcation with Ameri-Rack ARC1-PELY423-C3V3. It’s unclear whether the Unmatched supports bifurcation or not. Would be great if it did.
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Its very interesting that you decided to post about two ITX motherboards in a rack. This idea is my plan-B for the unmatched. Assuming my My64 case idea is too crammed and/or not really feasible, I want to try making a dual PC used for streaming and recording those streams and have one unmatched displaying per monitor and use something like Barrier to share the mouse and keyboard between the two. Of course this idea is ridiculously expensive for what it does, but I think it would be a fun computer idea.

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… Ugh – just got an email from Mouser that the HiFive Unmatched has a new estimated delivery date – June 1st… :weary:

I know it’s probably for the best. A reminder; “…there is no disappointment without expectation…”.

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On Mouser’s website it now says “930 Expected 5/28/2021”. Maybe they had to rev it.