Having a bit of difficulty deciding what hardware to get

[salfter]

Right now, I'm managing ~35 MH/s across four systems with a mix of CPU and low-end nVidia GPU (9500GT and 210...tried the Ion too, but got less than 1 MH/s from it) mining. My earlier CPU mining efforts actually generated a block, so I have some coin to invest in more appropriate mining hardware to bootstrap my way toward possibly producing a usable income stream.

At first, it looked like an FPGA miner was definitely the way to go, but after looking into things in a bit more detail, I'm not so sure.  Have a look at this spreadsheet I knocked together:

BTC calc spreadsheet

Electricity cost is what NVEnergy is charging residential customers these days.  (Electric cost for my existing hardware is a guesstimate, and not all-inclusive as one GPU miner is at work and one CPU miner is a Linode VPS.)  Exchange rate and difficulty were last updated earlier today.  This static analysis doesn't even try to account for changes in difficulty or exchange rate over time, but it shouldn't be too bad for drawing comparisons between different devices.

By my calculations, the options that will pay for themselves in the least amount of time are the BitForce Single and the Radeon 7970.  The Radeon is the cheaper of the two and is readily available (pricing is the lowest price available at Newegg; a quick check of eBay indicates I might be able to save a little bit more).  If ASICs end up taking Bitcoin mining by storm and render the Radeon useless for mining, I could always unload it on eBay to a gamer.  (I don't play games. I've stuck with nVidia GPUs up to now because they're dead simple to get running under Linux and VDPAU provides pretty effective HD H.264 and MPEG-2 decoding acceleration.)  OTOH, my home office is already warm enough.  250 W would be a fair amount of extra heat I don't really want or need.

The BitForce Single is more productive and uses two-thirds less power, but from what I've read, it seems like availability is a bit of a mixed bag.  It helps that Butterfly Labs takes Bitcoin directly for payment, but if I hand over a fistful of bitcoins today, how long would it take to receive hardware from them?  With the Radeon option, once I have some coins cashed out to dollars, I can place an order with Newegg and have the goods in a couple or three days.  80 W is another point in its favor.

The ModMiner and FPGAMining options also look interesting, though my finances would only allow a two-FPGA configuration at the start.  They'd earn about a third less than the Radeon or about half as much as the BitForce Single.  That would be that much more time before I can reinvest what they earn into more hardware (though the ModMiner could be expanded more frequently by adding one FPGA board at a time).  20 W isn't much more than a CFL lightbulb and would barely have an effect on my electric bill.  I haven't seen any complaints about availability or shipping delays.

Bottom line: I'm a bit torn as to which way to go.  The Radeon provides decent productivity at a lower cost, but would double as a space heater I don't need.  The expandability of the ModMiner is a point in its favor, as well as its frugal power consumption (which lends itself to acquiring a larger number of them as time goes on). The BitForce Single is the cheapest quad-FPGA option by a long shot, but how long will I be waiting if I put in an order for one?

Which option would you pick?

[ssateneth]

Wait, you recently mined a complete block from cpu mining?

You should play the lottery, because with luck like that, you would be a millionaire in no time.

[salfter]

Wait, you recently mined a complete block from cpu mining?

Not recently...think it was about a year and a half ago.  The prospect for that happening again does look somewhat bleak.

[Stephen Gornick]

Have a look at this spreadsheet I knocked together:

BTC calc spreadsheet

In that you show that you pay 11.4 cents per kWh.  That's average.  That isn't low enough to mine using a GPU where you will still be able to compete when in less than 100 days the block reward subsidy drops to 25 BTC per block.

If you had thee cents per kWh, maybe you could extend your GPU mining a bit longer, but at 11 per kWh, that isn't going to work unless the exchange rate goes up to $15 or more.  And if that is what you are counting on, why not just buy bitcoins and take immediate advantage of the exchange rate going up?

If you have GPUs and average electric rates or less, then milk them until December or whenever but do the math.  Half the revenue does not mean half the profit, it means for most everyone that you are then mining at a loss.  You are paying more for the electricity than the value of bitcoins you are receiving.

[crazyates]

That calc doesn't take into account a few things:

1) The BFL Single might pay itself off sooner than any other FPGA, but it also has ~60 day wait period before your item gets shipped.
2) Block reward half in < 100 days.
3) Difficulty is also rising, which means you will earn fewer BTC per day, even before the reward half.
3.5) When ASICs hit, the difficulty will skyrocket.
4) You didn't include any user hardware in that list. 5830s can be had for $80. 5870s can be had or $130. 5970s are about $250. User hardware might pay itself off sooner than current gen products
5) Have you thought about buying ASICs? It will be months before you do get your item(s), but the speeds are leaps above what today's hardware can do.

[salfter]

Have a look at this spreadsheet I knocked together:

BTC calc spreadsheet

In that you show that you pay 11.4 cents per kWh.  That's average.  That isn't low enough to mine using a GPU where you will still be able to compete when in less than 100 days the block reward subsidy drops to 25 BTC per block.

Yeah, I noticed when I cut the block payout to 25 BTC that nearly half of the GPU's output gets eaten up by utility costs. 

That calc doesn't take into account a few things:

1) The BFL Single might pay itself off sooner than any other FPGA, but it also has ~60 day wait period before your item gets shipped.

I found that in another thread.  I'd kinda like to get something going sooner than that.

4) You didn't include any user hardware in that list. 5830s can be had for $80. 5870s can be had or $130. 5970s are about $250. User hardware might pay itself off sooner than current gen products

Did you mean "used" and not "user?"  I had looked at eBay pricing for the 7970 and found prices in the high $300s there.  I just ran the numbers for the 5830...it would be cheap enough (might not even need a power-supply upgrade), but it would start out burning about a third of its earnings in electric costs.  Maybe if I use it to replace the 9500GT in my work computer...would probably need a new power supply to do that, though.

5) Have you thought about buying ASICs? It will be months before you do get your item(s), but the speeds are leaps above what today's hardware can do.

I have, but I'm looking for something more near-term.  Maybe whatever I end up buying can have its earnings directed toward adding an ASIC as the next upgrade.

One other thing:  I'd swear I saw the ModMiner backplane selling recently for ~$100.  Looks like it's now at $190, which raises the total price of getting into that.  It'd still be $250 per FPGA to expand it in the future, though, which would help a bit.

[crazyates]

4) You didn't include any user hardware in that list. 5830s can be had for $80. 5870s can be had or $130. 5970s are about $250. User hardware might pay itself off sooner than current gen products

Did you mean "used" and not "user?"  I had looked at eBay pricing for the 7970 and found prices in the high $300s there.  I just ran the numbers for the 5830...it would be cheap enough (might not even need a power-supply upgrade), but it would start out burning about a third of its earnings in electric costs.  Maybe if I use it to replace the 9500GT in my work computer...would probably need a new power supply to do that, though.

One other thing:  I'd swear I saw the ModMiner backplane selling recently for ~$100.  Looks like it's now at $190, which raises the total price of getting into that.  It'd still be $250 per FPGA to expand it in the future, though, which would help a bit.

Yes I did mean used, sorry. Those 7xxx cards are much more efficient than previous cards, but those 5xxx cards can also be very efficient when you undervolt them. My 5970s were getting about 3MHs/W.

If you're looking to not upgrade your PSU, look into this 7750. It's pretty much the fastest GPU that doesn't require a 6-pin PCIe power plug, and should be good for ~170MH/s.

[scifimike12]

If you're looking to not upgrade your PSU, look into this 7750. It's pretty much the fastest GPU that doesn't require a 6-pin PCIe power plug, and should be good for ~170MH/s.

I think you mean ~140 Mh/s.  To get 170, you'll need to overclock it past 1050 and most cards don't have voltage control (other than MSI).

[salfter]

I bit the bullet...or pepper, as the case may be. :-) In the meantime, I might still snag a Radeon 7750 (as suggested above) or 7770 to tide me over...it's not a huge expense, and even after ASICs take over the Bitcoin world (assuming for the moment that they do), it'll still be much faster than my 9500GT at cranking out vanity addresses and similar tasks.