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I need to build a (cheap) computer that might serve to:

  1. mine digital currency
  2. render 3D animations
  3. solve SETI problems
  4. ...etc

Basically I am just using the GPU's to solve math problems. I need very little live throughput to / from the cards.

My Question

Is there a way to:

  1. mount video cards through USB or Thunderbolt or some other chain-able protocol
  2. without writing custom drivers
  3. on a linux variant

There are some motherboards that support up to 6 PCIe connections, but it would be so much nicer if I could mount as many as the system resources could handle.

Not my question

  1. You would need to power them some other way. Got it. They all need external power.
  2. USB (and maybe even Thunderbolt) doesn't have the throughput for high-vector video throughput. Got it. I am not using these as video cards per-se. PCIE to USB/Thunderbolt for Graphics Card

Other, possibly interesting answers

  1. There is this clustering solution that... (likes gpu's?)
  2. There are these other processors that might be better suited... (asic?)

Discoveries made since asking the q

  1. Cluster of motherboards so cheap as to be irrelevant compared to the price of the GPU's, see this very interesting dissertation project video, alas... Raspberry Pi's and Arduinos don't seem to have PCIe slots. The HummingBoard-Pro does, but it is $55. My number needs to be under $25 each to be cost effective. Here are others: Gateworks Price Unk, Intel Galileo with mPCI, $45 each.

    • Samuel Cozennat gives us a gorgeous (but expensive) example using Intel NUC's. He includes the hardware build and provisioning setup. Very nice, Sam! Thanks.

  2. PCI-e can be split somewhat like USB and Thunderbolt... who knew? Here are a couple limited splitters: Amfeltec, C0C0C3. The PCIe spec indicates that it could theoretically support 32 1x devices.

  3. Thunderbolt has the capability (especially for low / non-video data-rates), but existing bios / mainboard / driver setups are not generally developed. There are some existing products that target laptops.

Sy Moen
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    I don't know, but I appreciate your "Not my question" section, as well as your formatting. – trueCamelType Apr 01 '17 at 04:35
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    @trueCamelType, you, me and Johannes would have been bad-asses in 1440... I guess he still is / was ;) – Sy Moen Apr 01 '17 at 04:52
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    So you want to possibly spend several hundred currency units on a graphics card but your budget for all other components is 25$? In addition "rendering 3D animations" isn't just math. As for your question just look for "external GPU" and you will have various hits.Though there probably is only a very small selection as even if you're saying you won't need a lot of throughput you will access RAM frequently. In addition there might be better solutions (digital mining) than graphics cards if you want to do "serious" work. – Seth Apr 03 '17 at 07:30
  • In the case of a cluster where each cpu supports a single gpu, yes, $25 is my limit per CPU/micro computer. Re 3D animations vs "math", I understand, but it is a very limited compute set for which GPU's are optimized. If I could find Blender ASIC's I would use them ;) – Sy Moen Apr 03 '17 at 07:35
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    Could you include more information about the scope/requirements/size of your planned deployment? Running a dual GPU solution it going to be wildly different from running a farm of hundreds of GPUs and actually specifying some kind of performance requirement would help as well. Right now one could suggest APUs or a farm of very old GPUs as well. – Seth Apr 03 '17 at 08:06
  • Well, the main question is less about the gpus (or apus) and more about the controlling hardware. Another way of framing the question is, "Can I reduce the hardware cost by eliminating the need for actual PCIe slots?" However, the scope is 10's at least and {n} theoretically. Indeed, not less than 25 in any case. – Sy Moen Apr 03 '17 at 08:57
  • I will have to add that there is a cost element in management which I may be overlooking. Maybe a $45 Intel Galileo to run each video card would actually be cost effective since the software provisioning would be so much simpler. – Sy Moen Apr 03 '17 at 09:06

1 Answers1

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What you are considering, although interesting, is likely not realistic without a whole lot of fairly complex low level software and reasonable amount of RAM.

Consider coin mining. The most realistic coins to mine today using a GPU are Ethereum, Dash or Zcash. There are others but these are three of the main ones. They all require a minimum of 2GB RAM to run which is not very commonly found on single board computers. They all require an active network connection so each would need to be connected via WiFi or wired. Linux would be the most likely OS selected due to the limitations and costs of Windows.

Coin mining software rely on the OS drivers and OpenCL or CUDA APIs to run the mining math problems in the GPU's which must be pretty powerful to perform adequately with a minimum cost of $150-250. The drivers and API sofware must be installed and would likely be very difficult to work using a non-standard connection such as mPCIe let alone how you would cable the mPCIe to the 16x PCIe connector on the GPU. Power is another big consideration and all of the GPU cards run on 16X PCIe and consume a minimum of 80-150 watts each depending on the miner and coin being mined. This would require an external power supply for the GPU's that have VGA 12v connections.

The best alternative is to get a multi-PCIe motherboard and PCIe risers. You can run 6 GPUs using standard hardware and software, lots of people have done this. Anything else would be interesting if you have lots of time to play but I believe you will quickly see the roadblocks would be very difficult if not practically impossible to overcome in order to achieve your stated 3 objectives.

Ed Stewart
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  • Would you mind expanding your answer to speak directly to either (1) pcie over thunderbolt or (2) how to get all 32 pcie channels on a single motherboard of any kind? – Sy Moen Apr 04 '17 at 19:51
  • I wish there was more of an answer, but I feel this really is correct. The fact of the matter (in April, 2017) is that the drivers and associated software just does not yet exist. 32 or more channels are quite possible for a single CPU, and they could be distributed via Thunderbolt if data throughput is not an issue. Someone interested (me, I guess) just needs to create a video card detector and proxy / bridge. Anyone in the animation / digital coin industry want to hire me for the job? ;) Thanks all! – Sy Moen Apr 06 '17 at 19:23