FPGA mining for fun and profit

[theboos]

This idea may have been discussed elsewhere, but what if someone produced a purely combinational logic circuit for calculating SHA-256 hashes. Such a circuit would be relatively small (low power consumption, easy to keep cool, easy to develop) and ridiculously fast, since you would get outputs as fast as you give it inputs. However, you'd need to develop one circuit for hashing the hash of the block header plus the nonce and another for hashing that hash (different input lengths). This isn't an issue if both circuits are combined, though it does double the initial computations needed for designing the circuit. Am I making some unreasonable assumptions here or would it be possible to achieve a multi-GH/s device?

[de4l]

based on the huge difficulty jump today.... I think someone has succeeded in fpga/asic bitcoin flooding

[kjj]

This idea may have been discussed elsewhere, but what if someone produced a purely combinational logic circuit for calculating SHA-256 hashes. Such a circuit would be relatively small (low power consumption, easy to keep cool, easy to develop) and ridiculously fast, since you would get outputs as fast as you give it inputs. However, you'd need to develop one circuit for hashing the hash of the block header plus the nonce and another for hashing that hash (different input lengths). This isn't an issue if both circuits are combined, though it does double the initial computations needed for designing the circuit. Am I making some unreasonable assumptions here or would it be possible to achieve a multi-GH/s device?

You still need clocking.  See here.

The idea of an ASIC (or FPGA, which is like an ASIC without the AS part) is to implement the logic such that all processing for each round is done in parallel, thus one round per clock.  You can then add pipelining to get an effective throughput of multiple rounds per clock.

[fpgaminer]

I think someone has succeeded in fpga/asic bitcoin flooding

That seems to be a common misconception present in this thread.

FPGAs aren't powerful. They're actually quite inefficient and slow  Read ArtForz's posts for a good breakdown and debunking.

Someone with free access to a huge stack of FPGAs isn't any better off than someone who has free access to a huge array of GPUs, as far as hashing power is concerned.

As for an ASIC, I highly doubt anyone is foolish enough to drop >$1,000,000 of their own cash to have developed one. Also, it takes a long time from start to finish. Bitcoins weren't all that popular a year ago. They still aren't (outside of our little bubble).

Suppose someone was foolish enough to do so. Well, sucks for them. Good luck getting $1,000,000 out of the Bitcoin market right now. The only feasible profit would be from selling them and spreading the risk to the customers.

I post occasional updates on my progress with FPGA mining in this thread. If I succeed in making FPGA mining feasible, I fully intend to release a product.

I also still have on my TODO list the release of an FPGA Mining Reference Design, open-source.

I hope this helps clear out the mis-information and fear. As always, I am happy to answer questions about my project, FPGA mining, and FPGAs in general. It's an exciting topic for me and I hope my knowledge can be of some use to the community.

[michaelmclees]

FPGAMiner, what else would explain the difficulty jump?  I'm thinking I ordered my 5850's at exactly the wrong time.

[kjj]

The goal is to have each block come out in 10 minutes, on average.

The difficulty target is increased every 2016 blocks.  So, if hashing power is growing, the blocks just before a retarget will be coming in much too quickly.  If the retarget shoots for a 10 minute average based on the pool at the time, before long we'll be spitting them out in seconds.

So, you calculate the rate of growth and extrapolate it out a week.  The first 1008 blocks take too long, and the second 1008 blocks are too quick.  Hopefully, if you guessed right about the pool growth, you get it more or less right overall.

[boscoj]

get me right, I know nothing of fpga's as they apply to mining but I can imagine a few implementations and also the potential for optimization . . .

http://upload.wikimedia.org/wikipedia/commons/0/07/Xilinx_S6-SP601_board.jpg

[JJG]

FPGAMiner, what else would explain the difficulty jump?  I'm thinking I ordered my 5850's at exactly the wrong time.

More people rushing in.

I'm sure a lot of people ordered hardware back when the exchange rate first jumped. Over the past week they've probably been receiving their hardware, configuring machines, and bringing their mining online. Meanwhile, popularity continues to increase.

We've all known that difficulty has been climbing at a rapid rate for quite some time now. These jumps shouldn't come as a surprise to anyone.

As for FPGA mining, it's been debunked many times already. FPGAs are good at what they do, but they're not magical.

GPUs, on the other hand, are really, really, really good at crunching lots of numbers in parallel. And they're relatively cheap.

[boscoj]

yeah well we just get the fpga to manage the arrays

[fpgaminer]

yeah well we just get the fpga to manage the arrays

Neat idea! An FPGA driven board, with PCI-e controllers and an ARM core in the FPGA. You could then run ribbon cable to quite a number of video cards, depending on how many PCI-e cores fit into the FPGA. Luckily we only need PCI-e 1x, which seems do-able with an FPGA.

My back of the napkins calculations couldn't justify the price, though. Perhaps for large mining farms. The majority of GPU mining cost comes from the cards and PSUs. Such a solution would only cut out the motherboard, CPU, and RAM, which really aren't that much. Not to mention how difficult it would be to get fglrx drivers running on such a stripped down system.

What we really need to do is buy the GPU processors in bulk directly from AMD and build massive GPU array boards  

EDIT:

FPGAMiner, what else would explain the difficulty jump?

Personally, I don't find the difficulty jump surprising. But to answer your question, it was the recent spikes in the market price, compounded by the naturally growing number of miners. Newcomers see the market skyrocketing like that and they all start firing up the machines they have lying around. We've gotten lots of new traffic over the past week or two from Slashdot, Reddit, and I think an article or two.

I know I just brought on an extra 3GH/s online this past week or so. Also take a look at how many posts we have about people trying to get their new rigs up and running, or looking to buy one.

To be honest, the difficulty increase isn't that bad. It's quite appropriate for the market price, which jumped from ~$3-$4 all the way up to $10 not too long ago. Regardless of the difficulty increase I'm going to break-even on my hardware in a timely fashion just as I had hoped. Probably before schedule!

EDIT2:
Almost forgot! The phatk kernel was released shortly after the difficulty jump before last (jump to 157K). This increased everyone's performance by 10MH/s or so. That was about a 3% increase for most people, which most certainly contributed to this larger difficulty increase.

[Chris Acheson]

Those of you voicing concerns about the possibility of Bitcoin being taken over by mining corporations with FPGA/ASIC clusters should check out the bounty thread for an open-source FPGA mining implementation.  Encouraging people to develop this stuff out in the open will help to prevent any one party from gaining too much of an advantage.

[Grinder]

FPGAMiner, what else would explain the difficulty jump?  I'm thinking I ordered my 5850's at exactly the wrong time.

You've pretty much answered your own question. There are probably a thousand other aspiring miners in the exact same position. It happens after every large increase in price, and combined with a Slashdot front page it's a disaster for difficulty.

[michaelmclees]

So my 1,000 dollar 1Ghs system isn't a total waste.  Fwwweeewww.

[cypherf0x]

based on the huge difficulty jump today.... I think someone has succeeded in fpga/asic bitcoin flooding

*bell ring*
We have a winner!

Two FPGA clusters went live.

I can't really describe the feeling of learning that the two initial units were for prototyping and there were RACKS of them to be used when idle.

[cypherf0x]

I think someone has succeeded in fpga/asic bitcoin flooding

That seems to be a common misconception present in this thread.

As for an ASIC, I highly doubt anyone is foolish enough to drop >$1,000,000 of their own cash to have developed one. Also, it takes a long time from start to finish. Bitcoins weren't all that popular a year ago. They still aren't (outside of our little bubble).

Very true, but what if there was already a source of something equivalent to high speed SHA-256 ASIC.

[PcChip]

*bell ring*
We have a winner!

Two FPGA clusters went live.

I can't really describe the feeling of learning that the two initial units were for prototyping and there were RACKS of them to be used when idle.

Does anyone here think the original creator(s) of BitCoin ever forsaw this happening?
If not, how do you think they feel about it?

[teknohog]

what if there was already a source of something equivalent to high speed SHA-256 ASIC.

There are SHA-256 ASICs around, but they are basically I/O limited. They are fine for getting a hash of some given string, but in a Bitcoin miner you are incrementing a part of the input in a specific way. This can be done inside the chip, so you don't need a particularly high I/O with the outside world.

[randomguy7]

I'm curious about that our 'mystery miner' bribes cypherf0x for not posting developement details, even if the main reason stopping the public to start FPGA mining seems to be the high price of the FPGAs (and a low hash rate compared to the high price). Even availability of some source code wouldn't make a difference at all because most people won't spend a bazillion dollars on FPGA clusters. Obviously mystery miner doesn't want us to know something. Maybe there's a quite affordable way to do fpga mining.
Does someone know the price to buy/rent copacobana? 

[Grinder]

Does anyone here think the original creator(s) of BitCoin ever forsaw this happening?
If not, how do you think they feel about it?

I, for one, welcome our new miner overlords.

This is the beginning of the end for bitcoins. Those who control the mining control the coins. If you're a big enough fan you'll probably be able to convince yourself that it's still better than normal fiat money, but the average person won't.

[anisoptera]

And you think people will go along with centralizing this much economic power into so few hands? Satoshi deliberately  designed Bitcoin to distribute wealth because he knew that if it didn't then it wouldn't be adopted. If this news spreads, then Bitcoin is going to be worthless before 21 million BTC has been mined.

It's not like FPGAs are some secret inaccessible technology. They are just expensive. Know what else is expensive? Four 6990s.