Localbitcoins is good and fast. I have sold over $5,000 worth of bitcoins with them in Australia.

They have escrow, so you can verify the funds are in your bank account before release of bitcoins.

If the trader uses the same bank as you, and responds quickly, the whole trade and verification can be over in less than 5 minutes!

Some traders do cash deposit to your account, which is also good.

Cheers.

I just noticed...
Feb 28 2014 difficulty = 3,815,723,799
on Feb 28 2013 difficulty = 3,651,012

That's a 1,000+ times increase, so a 1 TH/s miner today is only mining as many bitcoins as a 1GH/s miner 12 months ago.

Over the same period the bitcoin price has only increased about 20 fold (~$30 to $600).

Let's hope this rate of increase doesn't hold up for all of 2014, or in 2015 we'll be looking at ~0.004 BTC/month from a 1 TH/s miner!

Hi,

I started GPU mining in early 2012. In September 2012 I ordered a BFL 30GH/s Little Single that was delivered in September 2013 (somewhat ironically, about 8 hours after I left on a 10 day trip...).

I decided to sell that on eBay in October (mainly because of the difficulty going up ~40% per 10-12 days). I got $AU1125 for it (more than I paid), but I bought a 96GH/s BitBurner Fury on eBay a couple of days later for $AU1,575, and that is my current capacity.

No plans to upgrade at the moment.

Cheers.

You certainly were lucky! 

As already mentioned by al.matic, the mean time to generate a block at 20 GH/s is currently over 4 years!

If you are interested in the calculation, the formula is:

mean time (seconds) = difficulty * 2^32 / hashrate (hasrate in in hashes/sec, i.e. 20 x 10^9 for 20GH/s, and current difficulty = 609482679).

Even for a 100 GH/s miner the mean time to generate a block is about 10 months, and at 1 TH/s you could expect an average of around 1 per month.

Try https://localbitcoins.com/ - perhaps not so good with PayPal (although some people there use it), but you can buy with cash, bank deposit or bank transfer using escrow.

It also has feedback like PayPal, so you can pick a good trader.

Cheers.

I didn't know that - thanks!

That earning rate (0.013 x 24 = 0.312 BTC/day) sounds too high to me.  I'm mining at slightly under 100 GH/s and only get about 0.06 to 0.08 BTC/day at the latest difficulty - that would equate to 0.14 to 0.18 BTC/day for 230 GH/s.

I think the biggest problem with the setup you're looking at is the power consumption - according to https://en.bitcoin.it/wiki/Mining_hardware_comparison the Avalons use 620W each - 1860 Watts is a lot to pay for, and a lot of heat to get rid of!

Good luck!

Free power is always good!

I'm currently mining at ~96 GH/s using a pair of BitBurner Fury cards (~150W total). Since the last difficulty increase to 511M, I mine about 0.09 bitcoin per day (about $US25 at the current exchange rate).  This works out to about 26 cents per day per gigahash, which means if I was still mining with my Radeon 7950 GPU I would get around 10 cents per day (perhaps 0.0004 BTC).

Anyway, cheers and good luck!

According to http://mining.thegenesisblock.com/, you may be able to make some profit on this, perhaps doubling your investment over the 12 months of the contract.

Of course it all depends on Bitcoin price and difficulty increase.

btw: when evaluating a mining contract, just set the power consumption to 0.

Cheers.

I saw some very interesting issues raised in your paper.

In particular, I agree that the reward halving every four years is unjust and unnecesarily abrupt.

Cheers.

Hi,

I'm not trying to be a troll, but why would you want to mine with a GTX295?

Accoring to https://en.bitcoin.it/wiki/Mining_hardware_comparison you could get about 100 MH/s using 289W.  For about $20 you can buy a Asicminer USB block erupter that only uses 2.5W and mines at >300MH/s - check out ebay!

Cheers,
o999.

Hi,

Realistically CPU and GPU mining aren't anywhere near worthwhile now.

At 300 Mh/s you may make 20 cents a day which won't come close to paying for the 150w+ needed to run your GPU.  You can get an Asicminer USB block erupter for under $20 which has the same hashrate as a fast GPU but only takes 2.5W of power, but even with this you are unlikely to break even IMHO.

Have a look on ebay for "ASIC Bitcoin" or "Bitcoin miner" to see some options.

Cheers,
o999.

I see from the rankings table at BTCGuild that their fastest miner is 21 TH/s (21,310.98 GH/s) and the 25th fastest is about 6TH/s (5,969.28 GH/s), whereas at 98 GH/s I am number 1583.

I am interested to know the relative contribution of miners at various speeds to the total hashrate.

From looking at the top 25 on BTC Guild I can see they contribute 228,359.53 GH/s, which is about 20% of the total hash rate of the pool (1,147 TH/s at the moment), and almost 6% of the total bitcoin network hashing power.

Is there still a big contribution from smaller miners (say 10GH/s or less)?

I would definitely be interested in finding the mean/mode/median for miner hash rate. Any ideas on availability of this information or how to extract it?

Cheers,
o999.