I'm fairly new here - and only mining for curiosity.

This is the second invalid block in a few days - does it happen often or is this unusual?

What's to stop a miner in a pool who finds a block from taking it for himself and modifying the miner software so he returns it to the pool just a bit late?

This thread was from last May.

Hardware that was viable then is now completely redundant and will never get near mining a single bit coin.

If you don't understand how the increase in difficulty in the bitcoin process makes this happen then you really need to go back and read a lot more before you even think about buying mining hardware.

John S-L

P.S. the link Serje provided, above, gives similar figures to mine (slightly different difficulty estimate - but similar profile over time).

Any return calculation that is based on just the current difficulty will be wildly off track after just a few weeks.

John S-L

No, it is not good.

In my opinion 1.1 Th/s will earn you (if you start right now) :

3.6 BTC in 1 month (and you'll seem to be onto something good)

... but ...

only 7.7 BTC in three months (inlcuding the 3.6 above)

and only 11.6 in one year (including the 7.7 above)

... and will grind to a virtual standstill with only 11.8 in two years (including the 11.6 above)

Increasing difficulty is the key factor in killing this - will be more than 10 % harder in 4 days.

(P.S. It'll cost you 1 BTC of these totals if it takes a week before you actually turn on).

Power consumption and other support costs will increase the outlay and I don't believe the operation will ever make a return.

Discounting the change in value of bitcoins. As you can (as others have suggested) invest in bitcoin future by simply buying them now.

Private mining at these hash rates is not viable at any where near this level of entry cost per Th/s

Somewhere around month 5 or 6 the return will become so low that you will look to sell it (if you do the maths) - the only silver lining is that resale prices on old mining hardware are insanely high so your kit with a total residual mining capability of perhaps only 1 BTC could sell for much more that it really ought to. 

If you believe in Bitcoin - buy them.  If you want to mine them get your hashes more cheaply - much more cheaply - and roll in your infrastructure and operating costs.

John SL

The increasing difficulty and reducing payout per block mean that Block Erupters already have a trivial value and will fairly quickly be entirely worthless. There is no 'leave it on and after a long time it will return something'.

I did some calculations last Monday (St. Patrick's day - I'm Irish) :

If I started mining (24/7) with a Block Erupter on March 17th then the Bitcoin returns would be :
In 1 month : 0.0011 BTC   =  USD 0.69
In 3 months : 0.002357 BTC  =   USD 1.48
in 1 year : 0.003549 BTC  =  USD 2.22
in 2 years : 0.003603 BTC  = USD 2.26

So it will earn only 4 US cents from Paddy's day 2015 to Paddy's day 2016 (and use 43Kwh of electricity in doing it - not including the power costs of the infrastructure)

There are approximations in this (pool type - hardware growth [i.e difficulty changes] etc) - but if anything they are conservative as the more power that comes on stream the higher the difficulty curve goes and the sooner these little USB miners become completely worthless as miners. 

The residual value from selling the BEs on Ebay is by far the most significant factor in their current value - so sell 'em while they're still worth something.

The same maths worth for any  piece of mining hardware - the only question is where on the curve it is - but pretty much everything on sale on Ebay (even the newest, fastest and least power hungry of the USB miners) is selling for more than its medium turn return and most are selling for more than their total future return.

And if the underlying belief is that BTC will increase in value enough to make it worth while - then the correct response is to invest in existing Bitcoin.

John SL