I'm extremely busy trying to hit the May 30 launch date so I don't have a great deal of time to follow this thread, and I have so many PM's I can't possibly read/respond to them all. However I did glance at some of the common questions and I thought I would give some short answers:
- I've been contacted by many big farm owners and so on, and for them as well as anyone who is hesitant, please just wait for proof. The only real proof will come when guinea pigs like Ruplikminer get their hardware in the end of May and start hashing and reporting back. Don't worry about a shortage of cards; Xilinx and Bittware are preparing for high volumes
- Of course I considered renting Amazon AWS F1 (VU9P) FPGA instances and mining with them since you can make 4x more than the rental cost of the FPGA. However by all accounts Amazon has some sort of watchdog software and if it catches you mining, your instances gets shut down. Most people report being shut down within 8 hours if they try renting FPGA's with Amazon and mining with them
- I'm trying to help the crypto community move forward and as such I'm happy to help as many other FPGA developers as possible. Digitalcruncher came very close to my Keccak hash rate with 24 Keccak instances @ 550MHz. What most people might forget is you don't need to calculate the full 256-bit hash in the FPGA. All you need is the top 48-bits to see if it is less than the target, pass the winning nonce back to the PC and the PC will regenerate the full hash using the nonce. So start with the 48-bit hash fragment you are interested in, and propagate backwards to eliminate calculations; this eliminates most of the final round of the algorithm, and the same optimization applied to the 1st round yields similar benefits. Then, for S-boxes always use compressed combinational logic forms that have been published, and try running them through an Espresso logic minimizer like Logic Friday, which can sit there for 2 days optimizing your S-box (vs. Vivado which will not spend more than a few minutes trying to optimize it during synthesis)
- USB data transfer rate is 12MBaud so it is fine to use USB2 ports. Technically you can have way more than 8 FPGA cards on a single PC, with lots of PCIe-USB adapter cards; eventually the load on the CPU and RAM will become high, so for a 16-card rig with two power supplies, a heavier duty CPU and RAM might be necessary and I can't vouch for the stability of such a big rig
- I hear Avnet only ships to North America. The VCU1525 is available from Digikey for around $4500 USD and they ship internationally. Bittware is really the best of the companies and is the only company that will actually help you configure (or even pre-configure) your card and if you have problems they will help you 1-on-1 because they are a smaller company and they will be mining with some of their own FPGA's (and Bittware will ship internationally no problem). Plus the Bittware card can do Xevan and Equihash better than the VCU1525.
- All stratum communication is done by the PC with a fork of tpruvot's CPU miner which has been adapted to communicate with the FPGA's. The PC-side code is a messy hack right now, so I have enlisted a good friend in Spain to help clean it up for the launch and make it more user friendly and resilient. I have been contacted by three super-expert FPGA programmers and after the initial algorithms are launched I hope to make it more of a group effort to get the remaining algorithms implemented faster with their help, so if I were to die/disappear the project would continue
- You can calculate how many FPGA's each coin can handle before miners overwhelm the coin and profits drop. You have around 2.9 BTC of daily rewards available on Keccak and over 20 BTC of daily rewards available on Phi1612, enough to support many hundreds of FPGA's, however as more algorithms are released, we will start hitting the huge coins and I don't foresee a dramatic and sudden profit drop as usually happens with ASICs
- It takes 40 seconds to switch the FPGA from one algorithm to another using Xilinx Vivado Lab Edition; this can be done remotely if you live away from your farm, but it is not automatic like for GPU's
- It is possible by using data from initial algorithms to project the hashrate within +/-10% for future algorithms, and in that light the expected rates (per card) are about 300MH/s for X17 & X16R, 25MH/s for Neoscrypt, 600MH/s for Lyra2v2; 150MH/s for Xevan (Bittware card only for Xevan!). For Equihash it is much harder to calculate the projected hash rate. I don't think Ethash would be profitable enough to be worth it. Those numbers are just projections though, and their profits are in the same range as the initial algorithms being released, with X16R and Xevan looking the best at around $75/day
- X17 and X16R require two FPGA cards daisy chained together with 2 x 100G ethernet cables, one FPGA does half the function, the other FPGA does the other half
- Xevan requires FOUR FPGA cards daisy chained together with 6 x 100G ethernet cables; this is only possible with the Bittware card
- The QDRII+ SRAM modules for the Bittware board are very expensive: $2250 for one 76MB module, four modules max per board (288MB max). This is the way to do Equihash but I have not yet been able to calculate if the price of the memory is worth it for the increased hash rate
Stay tuned for the end of the month launch and I hope that answers most of the important questions.
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