Re: ZTEX USB-FPGA Module 1.15x: 190 MH/s FPGA Board now on stock
You're right. 
Sorry about that. I pulled the wrong numbers so the output was too high for both FPGA and GPU. I have updated the calculations, which now shows that FPGA and GPUs are roughly equivalent at 8 cents/kWh, everything else being equal.
Sorry about that. I pulled the wrong numbers so the output was too high for both FPGA and GPU. I have updated the calculations, which now shows that FPGA and GPUs are roughly equivalent at 8 cents/kWh, everything else being equal.People should run their own numbers in any case your $/MH on the GPU farm is higher than my actuals by about 25% but people build with different degrees of efficiency.
You're certainly making the point that FPGAs are now in the realm of competitive for new deployments, even for buildouts with fairly short term planning horizons. Ztex's modules are also attractive because they've clearly been designed in a manner which would facilitate re-purposing them for things other than mining, which is a reason they should retain some value even if future SASIC (or even ASIC) devices are more efficient for mining.
OTOH, the density of one S6-LX150 per board is kinda poor, as I assume these are losing a fair amount to commons and PCB costs (the bare FPGAs are about $190 each IIRC). Sort of a tossup, the single chip boards are more reusable but it's still kinda pricy even with the quantity discounts.
25% less on your build? That's impressive. Care to share your secrets?
Very true: Do you own math/homework. Whether it's hype, anecdotes, or my calculations, it might not be right for you.
I'm ambivalent about the resale value of the FPGAs. If BTC was no longer viable or you just wanted to get out of the game, I think you would take a much bigger hit on the residual value of the FPGAs than a GPU.
Certainly they are being an option worth serious consideration. Multi-FPGA and better hash rate at a lower cost is what could be very interesting. Keen to hear about the 2nd gen....