Topic: 8 GH/S down to ~ .05 BTC/day (Read 1188 times)

Difficulty changes about every 14 days. Assume an ~20% increase each time, then see what numbers you come up with...

Example:

400GH/s BitFury... 28 days?

Assume difficulty changes biweekly, one after the first week, and one after the third..etc..:
After...
First week 25% is paid for (assuming your ROI of 28 days with constant difficulty correctly equals 100%).
Second week difficulty goes up 20%. So, you pay off 25% * 80% = 20% more (total 45% paid)
Third week: same difficulty.... +20% more = 61% paid
Fourth week difficulty goes up 20%. So, you pay off 20% * 80% = 16% more (total 77% paid)
Fifth week: same difficulty.... 16% + 77% = 93%
Sixth week difficulty goes up 20%. So, you pay 16% * 80% = 12.8% more (total 105.8%).
>>You actually broken even 7/12.8ths into the sixth week or 3.82 days into the sixth week.

5 * 7 + 3.82 = 38.82 days to ROI. A (10.82/28 * 100)%, or 38.6% increase in ROI time.

Quite different when you factor in difficulty.

Caveats: Assumptions made were that difficulty increases by 20% each time. However, this can change even to the negative.
But seeing how BFL is shipping still, this is not likely to go negative. And the assumption of minimal system down time.

Edit: If power costs were not factored in the original, this would take even longer... perhaps another four days to a week.

A BFL sc is 0.47BTC a day the roi depends on what you paid for it, the 60GHs at $1299 would be 23 days,
 If you paid $2499 for the 50GHs (0.39BTC a day) roi is 53 days from now.

This is all assuming free power and no difficulty change LOL.

What is the cost and the speed?

What would the equivalent for an Avalon unit be, given the cost and speed without power consumption and availability taken into account?

After the recent difficulty increase 8 GH/S is down to about .05 BTC/day.

In related news...

So a upgraded Jally after the price hike is ~.05 BTC/day (71 day ROI starting today)
a 400 GH/S Bitfury unit is ~2.5 BTC/day (28 day ROI)
a BFL minirig 500 is ~3.1 BTC/Day (63 day ROI starting today)
an eruptor  is ~.0002 BTC/Day (about 2000 days to ROI?)
a Monarch is ~3.75 BTC/day (11 day ROI if it started running now).
KNC Jupiter is ~2.5 BTC/day (ROI about 24 days)