do what Im doing and buy up 2nd hand 5970's.
They have a ROI of about 3 months
That could be misleading. Even if the cost of electricity is not being figured into the equation and you find a steal and pay only $350 for a good, working 5970, you are still close to 5 months.
If ROI is the term being used, then ROI is negative until the accumulated operating profits equal the amount invested.
So to calculate ROI you need to calculate operating profits. The known variables of price per kWh, cost of the hardware and the hashing strength of the hardware are known. What is unknown is future exchange rates and future difficulty levels.
At today's difficulty level a 5970 earns about half a bitcoin a day, and electricity at the U.S. average of $0.15 per kWh means it costs a little over a dollar a day in electricity, a little more when adding in the draw for the mobo/psu/display. So that's about a year to reach breakeven, just on the cost of a GPU itself (0% ROI). That is, assuming, the exchange rate to difficulty ratio doesn't doesn't move against you in the meantime.
Yep all factored in, I should quote that YMMV
It also assumes constant prices etc which is false, just a rule of thumb.
Your electricity in the states is nearly as bad as mine in AU (0.22c) - I managed to save on power by running the miners at a commercial area that gets discounted rates
Ive been super lucky so far, my 1st two I scored for under $300 ea (got my eyes on another for $230 right now).
I should also note I push my 5970's very hard.
I guess I got the answer I was looking for here in post #2...https://bitcointalk.org/index.php?topic=66314.0
Seems like BFL is intentionally trying to sound misleading. The actual chips that do the mining work, the part that matters, is not ASIC compatible. Only various components that connect to the board naturally are. Kinda shady IMO. BFL knows that ASIC is an exciting buzzword right now as it relates to bitcoins. I wish they were more clear on that.
That is BFL through and through.
They are FPGA's with some little atmel chips on there which at a guess provide hardware monitoring and possible the uART's used to communicate with the FPGA. Thats where their asic claim comes from and you are correct it is intended to be purposefully misleading just like their advertised shipping times.
My electric rate is .11 kwh,mining with 1-6950 & 2-6970's I get 1.6 gh/s.They consume about 1000 watts together.It costs about 65% of my earnings to pay for the extra electricity.
With the BFL single's I can run almost 11 of them for the same amount @ 8.8 gh/s,reducing overhead by 8x
I'm buying these (BFL's) with earned BTC from my GPU's (no more cash out of pocket,since buying the GPU's) & will sell off my GPU's when I get 2 BFL's running & will buy more as the BTC are earned.
ROI is about 4-5 months in my case because of my current GPU's making up the difference.I used 2 million as the difficulty @ $4 per BTC for my calculations.
As for Ztex,X6500 & other FPGA's (singles) the ROI is around 12-15 months,even with my GPU's helping.
Yes BFL's shipping time is crap,but I'm patient & willing to wait for them,the shipping times seem to be coming down slowly.
Hope my scenario helps you decide
Good Luck Paladin69 !!!!!!!!!
Thats a good plan and basically what Im doing (but about 8 months behind you). If you can keep your initial investment amount low things get much easier.
BFL currently is definitely the clear winner for pricing atm. Given their ~3month shipping (3 months of them grinding bitcoins out on your single to help pay production costs) delay it still has a better ROI time that any other FPGA currently.
Keep on mining them bits guys