Post
Topic
Board Mining (Altcoins)
Merits 1 from 1 user
Re: DIY FPGA Mining rig for any algorithm with fast ROI
by
GPUHoarder
on 05/05/2018, 14:16:50 UTC
⭐ Merited by 2112 (1)

Still working on it, it “runs” 22kH but not completely convinced a good portion of that isn’t spitting errors. I’m using a relaxed definition of correct to squeeze higher hashrate out while allowing some rare corner cases to be incorrect. Currently more hashes than expected are incorrect.

Well 22khs is pretty descent, the guy who claims VCU1525 gets 64khs is R0land

I won’t say it’s impossible, but I would be really genuinely surprised. 32MB / hash of total bandwidth (read + write) is needed, and 2MB or so of stashes per hashcore.

You have 1280 URAM blocks of 288kb by 72 bit interface dual ported in the biggest configuration .That’s an incredible amount of internal bandwidth but you can only store 23 or so simultaneous Cryptonight7 2MB blocks in that. The absolute biggest part (which isn’t on the 1525 board) has 360Mbit URAM, 96Mbit BRAM, and 48Mbit Distributed RAM, holding a theoretical 63 MB of pipelines, assuming you didn’t need a single bit of that for the rest of your logic (you do).

The external memory at say 4x64 DIMMs @2666 is only 85GB/s, or 2.6 KH worth of bandwidth with a perfect access pattern.

Even if you could imaginarily use all 2000+ balls on the FPGA for 2666 MT/s DDR style  speeds you’d still only clear 20KH against external memory and that isn’t even real bandwidth.

 Even if you took the biggest part with 128x32 Gbps transceivers to SERDES memory you’d only have 16kH limit from bandwidth.

Unless you break the algorithm itself, there’s no where to find the bandwidth + storage space for 64khs on a single FPGA.