Oh god, the stupid you exude is painful. Alright, math boy, lay out the simple math that illustrates how FPGAs are more cost effective for you. This should be amusing...
Laugh away
My electricity cost is €0.15/kWh. I believe the numbers below reflect current best-in-class GPU vs current FPGA boards. (I don't mine myself but they'll do for the calculation).
$8/BTC:
FPGA: 100Mhash/s @ 7W = $0.45/day at a cost of €0.15*24*0.007 ~ $0.035 : (13x)
GPU: 800Mhash/s @ 350W = $3.62/day at a cost of €0.15*24*0.35 ~ $1.76 : (2x)
... and, as I project and as you seem to claim, the price of BTC is going down:
$4/BTC:
FPGA: 100Mhash/s @ 7W = $0.23/day at a cost of €0.15*24*0.007 ~ $0.035 : (6.5x)
GPU: 800Mhash/s @ 350W =
$1.81/day at a cost of €0.15*24*0.35 ~
$1.76 : (1x)
So. Looking at electricity costs at $4/BTC with all other factors equal (difficulty) GPU miners will need to pull out completely, even if they've paid off their rigs. FPGA miners can continue, with a longer expected ROI.
The point is, upfront costs are irrelevant when you take the long view. I consider mining bitcoins to be just as mining any other form of natural resource. The price floor is at extraction cost (plus minimal profit), anything above that is speculation. Since I agree with you that speculation won't continue to drive BTC price in the near term my projection is that the floor is where the cheapest mining can be had. Currently that's FPGAs, but they will be replaced by ASICs. GPU miners, like CPU miners already have, will need to drop out.
YMMV - and I expect you'll point to investment costs and ROI. That's where we can have differences of opinion
[at $0.2/day it will take years to pay off an FPGA miner. At $0/day it will take even longer to pay of a GPU rig]
