Bitcoin Forum

Hi Bitcoin Folks!

I've got a few questions about FPGA Mining

What exactly is an FPGA Miner? I've seen links to buy FPGA Board/Cards, but how do they work?
Are they PCI type cards for a PC? If not, how do you configure one to Mine / Pool Mine? (Can they pool mine at all?)

What's the profitability of one too? I'm guessing one running at about 250MH will use the same power as something like a Sky box, which is normally switched on in a house 24/7 so electricity usage wouldnt change much!
How many BTC/Month would this bring @ 250MH?

I'm thinking of buying one. But I want to know everything about how they work first.

I've seen them with ports such as audio and usb etc, but just how would I configure and use it if I Bought one??
I want to buy one, but only after knowing all the ins and outs of it. Electricity costs, cooling, how to configure. Etc

Can anyone shed some light on them?

It's a small board with a special (FPGA) chip on it. You connect it via USB to your PC and feed it with 12 Volts. The bitstream is loaded to the FPGA via USB. Ztex has an easy to use software ready. The main advantage a FPGA board has over a graphics card is that i uses a lot less power. About 30W (3 ztex boards) compared to 200+W for the newest GPU for around 600 MH/s. You can make about 20 to 30$ per month with 250MH/s without power cost ! Most boards won't run that fast with one chip.

For questions about FPGA itself you should ask people like ztex, rph, eldentyrell or artforz.

Logic functions (like hashing SHA256 function) are processed by gates connected in proper way. FPGA is a electronic component called chip with milions of gates and interconnects inside (just like CPU or GPU) but that interconnects between gates are not defined by manufacturer (in CPU,GPU are). You decide how to connect those gates between each other and in a result what function that FPGA will perform. You are doing this by downloading a bitsream to them (you may consider this as loading program). Some boards have some sort of non volatile memory so this process can be automated and loading bitstream wiil occur without user interference. When FPGA will be "programmed" you need to download a data to process. This is mostly done by a PC computer with proper aplication running on it, and dowlading is thru USB. In that aplication you can set a pool, user name,password and other stuff if needed.
Here in forum you can find offers of boards designed specially for mining with program in it, so just plug to computer USB, to power supply, run program on PC, set and mine. Profit.
Advantages of FPGA's are:
-10 (more or less) times less power consumed than GPU with the same hashrate
-less heat
-less noise
Disadvantages:
-price
-almost zero resale value.
Thats a short version of FPGA story :)

Don't forget to mention Icarus from ngzhang (https://bitcointalk.org/index.php?topic=51371.0) with 380MH/s @ 20 watt ;)

http://bitcoinfpga.com/

Butterflylabs said they are shipping their first round of production soon.  Who ordered one?  They seem to be a good plug & play option...

They look a bit scammy to me.  They say 4-6 weeks for first product.

And they've been saying 4-6 weeks for quite a while now. At least photos are turning up now and again. I'll buy one as soon as customers start receiving them. Until then I'll keep my 5870s going.

I'd also like to point out the X6500 FPGA Miner (https://bitcointalk.org/index.php?topic=40058) from fpgamining.com (http://fpgamining.com). There are a lot of X6500s out there in the wild and a lot of talented and enthusiastic folks willing to help you get started mining. The other options are interesting though, so check out all of them! If you have questions, you can find help in #bitcoin-fpga on Freenode.

http://dl.dropbox.com/u/13472215/x6500_s.jpg

I completely concur.  I actually e-mailed them and had a few exchanges back and forth.  This is an exact quote:

"we're just preparing our first shipments now.  Stand by for a few days and you'll see units in the wild."

I look forward to speaking with someone actually using one.  B/c the price for the 832 ghash model isn't bad, especially if it's quiet, cheaper electricity, easy to setup, etc.

One thing I'm seriously surprised is that there isn't one FPGA bitcoin miner available on ebay.  Not one.

I thought there would be at least one listed in the secondary market...  Must mean that it is very profitable to use it rather than sell it... :)  I hope to be a user soon!

ebay generally dislikes the term "bitcoin"

and they will ban you at anytime.

oh?  Did I miss some news?  Is ebay banning the sale of bitcoins?

I know I saw a ton of "bitcoins" listed on ebay and it didn't make sense to me.  Did ebay have troubles with the transactions/scammers?

I know 5970's are labelled as "bitcoin mining ready" all the time, so I don't know why a "bitcoing mining FPGA" rig couldn't be listed.

I can't find any FPGA bitcoin miners on ebay though...

What I don't understand is why anyone would buy them besides shits and giggles. Maybe if you're really limited on space/heat/noise and REALLY want to be a miner.

At $600 for 360mhash you can build a $600 rig that makes you twice as much money. Pays itself off twice as fast. That's including electricity costs. There's very little resale value which means a lot more risk. Maybe I'm missing something.

The biggest bonus I see is FPGA making you money when BTC is under $1.50 USD. If BTC is that low, I'm not feeling good about my FPGA investment regardless.

When the total network hashing power get higher you get less BTC for your shares.
So if the BTC stays at the same price but the network speed gets 10 times as fast, and normally you need 10% of your BTC to pay the bills for the electricity, you now need all of your BTC to pay for electricity.
FPGA's are about 10 times as cheap in electricity consuming so they will rise from 1% of your BTC to 10% of your BTC.

Well, some people, especially in the EU have very expensive electricity ($0.25+/kWh), from what I am reading on these forums a lot of people is US pay $0.10 or less..

Well the network isn't going to get 10 times as fast. However, blocks will give 25 btc in Dec 2012. At that point, at the same USD price, yes FPGAs will make a little more money then gpus. If the USD price goes up, GPUs are still better. At $6 it's about even (once blocks give 25 btc).

But that's 9 months out, and best case is FPGAs pull even or slighty ahead. The resale risk, BTCs USD value risk, if I had 10k to spend I'd still go with GPUs.

It's about diversifying.  I think if I add some FPGA's to my mining operations, then I'm more versatile to "turn off" certain rigs when it makes sense.

Also, your arguments of them paying themselves off in a few months are very short sited.  FPGA's over the course of a two years period could save you loads on electricity.

Also, if you are mining in your house, then you only get so much electricity before you have to start getting industrial lines taking to your garage...

FPGA's you can multiply your mining power by 10 and stay under the electricity ceiling that typical US Homes have.

And yes, my elctricity costs are $0.06 / kwatthour

When you have 10k to spend, you can get FPGA miners for a lot less than $1.67/MH.

Unless you have essentially free power/cooling -- it really does not make sense to
invest that much into a new GPU rig.

-rph

rph,

Is there anything to this 'rollntime' 500% performance bump that BFL has purportedly achieved?

https://bitcointalk.org/index.php?topic=53530.msg752254#msg752254

That's just nitpicking on the definition of efficiency. While that statement might make sense from a pool operator's point of view (roll-ntime + difficulty 5 => 5 times more hashrate with the same network traffic), it certainly doesn't from a miner's point of view.
There is no 500% performance bump, just a little less network traffic.