I have 4 pieces of feedback regarding FPGA mining on Ethash. I would like to know what evidence you have to support the claim that there are FPGA miners on ETH?
1. Memory bandwidth limitations on FPGA
FPGA’s are not viable for mining ETH as they are memory interface bandwidth bound. From a high level, Xilinx FPGA’s eg. VU9P/11P/13P chips, U200/250 boards and 1525 boards support DDR4 in up to 256 bits wide (depending on board layout). The DDR4 limitation makes FPGA’s uncompetitive (to low cost GPU’s like the RX580 at $100 street price compared to $3500-$10000+ for 1525 and U250 boards). I can do the bandwidth math if you need it but it’s too early in the morning.
You may be able to get GDDR5 and GDDR6 memory controller IP but I am unable to validate whether such IP exist and whether the business model is viable (ie. licensing fees). Internet searches yield zero hits on Xilinx boards with GDDR5 and GDDR6 memory.
2. Economics of mining on moderately priced FPGA
Most of the commercial FPGA miners are using VU9P or 1525 like boards. The ROI is relative long at $3500+/board for DRR4 or GDDR5 performance if you accept my memory bound assertion. Assume than the board is 50W and equivalent to RX570 at 30MH/s and you get an annual return of $12/month or $120/year which translates to 30 years ROI. Why would you not mine SHA3 or X11 or other Altcoins with higher returns?
3. Secret mining on FPGA
The hardware acquisition cost of VU9P and 1525 boards (now discontinued) are very high relative to ROI period. Why would you secret mine on FPGA when the hardware cost are so high at $3500+ per board?
If someone had a viable FPGA bitstream, they should sell the ETH bitstream and try to monetize the NPV (net present value) of the mining rewards for some portion of it by licensing the bitstream. However, you can NOT make enough money by mining ETH on FPGA’s … but then you will not sell any bitstreams if FPRGA performance levels are similar to GPU’s.
4. Known FPGA ETH miracles
There are 2 known FPGA ETH hardware fairy tales. They are:
A. Ubimust in Montreal with a 1.9GHs hash rate claim
The claim was widely echoed on the internet but the rig based on the 8x1525 boards never shipped and Ubimust does not list this product on their website. It is technicially impossible to get this type of performance on DDR4 memory.
B. Squirrel Research - Acorn boards
There was a claim by SQRL that ETH performance would be improved by 30% using low end FPGA board to offload Keccak processing from a GPU. Needless to say, this product did not work and the bitstream never shipped. Rumour has it that Kristie-Leigh aka OhGodAGirl of ProgPOW fame was involved in the bitstream development through her Mineority connections with SQRL.