Does anyone know if there exists a USB3 graphics adapter with opencl support?
Why would I ask about such a crazy thing? A friend of mine is heavily into digital coin mining and she
explained to me that the pciexpress bus speed didn't matter and that all the calculations were done on the GPU and
the results then sent back which didn't require much bandwidth at all. I've been playing around with some rasberry Pi's
and it suddenly occured to me that if there existed a USB graphics adapter that supported opencl then I might be able
to use one (or possibly several with a usb hub) to mine digital currency on a rasberri Pi, Orange Pi or similar computers.
Why try and do this and not just use a cheap motherboard? I'm pretty sure that this won't be economical either. The answer? Because it's cool and fun. All this presupposes that there exists a USB graphics card that supports opencl, so please let me know if you know of one.
There are USB-based ASIC miners, but depending on what coins she's mining they will either be too slow to be worth the electricity they consume, or be resisted by the hashing algorithm (Scrypt is usually ASIC-resistant).
OpenCL is a general-purpose compute layer that just happens to be nice for using GCN graphics processors to mine scrypt coins. It's not just going to be supported by a USB miner. It's faster to just engineer an ASIC that performs the hashing calculations directly rather than just translate it for a graphics processor.
So, USB miner chip? Yes. Sort of. OpenCL support? Almost certainly not. Because implementing it for something that specific makes no sense.
And with Raspberry Pis, you'll be restricted by bandwidth quite a bit because the LAN port and all the USB ports are on a hub, so they'll all be sharing the same 480mbps connection, only leaving you with a maximum theoretical bandwidth per ASIC of about 120mbps, which is 12MB/s. Given that these ASICs are capable of several gigahashes per second, you're going to be severely limited by the USB bus. That's why they all use USB3.0. Bandwidth DOES matter quite a bit, it's just that graphics cards are not fast enough to saturate the massive PCI Express bus with what they can do, even a PCIe Gen2 1x connection, because that's still quite a lot of bandwidth for mining coins at the rate that even the fastest GCN cards can.
But you should know that those SHA-256 ASICs are selling for a dime a dozen at this point because they consume significantly more electrical power than they generate in currency, because the currencies that are worth anything are so difficult that even multiple terahash ASIC mining machines are no longer profitable. Keep that in mind. It's a fun project, I suppose, and those ASICs might have uses if there ever arises another application for ultra-fast SHA-256 hashing, but for a coin mining operation to be financially viable at all, you have to have balls/ovaries of cast iron and a sense for economics bordering on precognition.
I already know that it wouldn't be cost-effective. I stated that in the previous post. I just wanted to try it for fun.
then yeah, go for it.