I'm trying to understand the cost per hash operation with Litecoin vs Bitcoin over time. The theory is that the network that has the best prospects for long-term security (via hashing) will set a standard that may influence its own price.

Specifically I'd like to compare

  • Capital outlays (reasonable mining hardware ASIC vs GPU)
  • OPEX (Electrical, etc)

Suppose I were to compare BTC/Litecoin mining to ore mining. Once the ore is extracted and purified, no more cost is needed other than to secure the facility where the gold is stored.

Its clear the mining process is technology dependent (ASIC vs GPU). What isn't clear to me is once the technology matures, what approach has a greater chance for long term efficiency for maintaining and securing the network.

I suspect that the scrypt -vs- sha256 implementations will have different power requirements, and I'd like to understand which one is "greener" for the environment in the long haul.

Any information relating to

  • Cost of current mining rigs to power efficiency

  • Cost of future mining rigs and projected efficiency

Would be very interesting.

  • "Cost of current mining rigs to power efficiency" This depends directly on the exchange rate, so this is less of a question about which will use less energy and more about human irrationality. – placeybordeaux Mar 8 '13 at 21:19
  • @PeterMichealLacey-Bordeaux I'm not talking about profit, I'm referring to capital and operational expense, which should be fixed. Revenue is a different topic I didn't want this confused with. – random65537 Mar 8 '13 at 21:32
  • I am a bit confused, you are talking about captial and operational expense, but for what? You can mine both of them on your phone if you really wanted to, but the return would be really really small. – placeybordeaux Mar 8 '13 at 21:44
  • 2
    @PeterMichealLacey-Bordeaux - You're thinking ROI which takes price into consideration. I'm thinking only of return on hash power. BTC was once a lose-only proposition. It has appreciated to profit for various reasons. – random65537 Mar 8 '13 at 23:06
  • What has a lower long term cost per hash It's not particularly relevant what the cost per hash is - if the hash is 100 times easier to compute, then it will be computed a 100 times more. – Nick ODell Mar 9 '13 at 3:44

One of scrypt design goals was to make CPU and GPU performance balanced, which meant that it was far more dependent on memory speed.

The GPU had a solid work around and as far as I know CPUs don't have any advantage.

But that did cause it basically impossible to do scrypt mining with an ASIC unless it has a ton of memory and memory channels added in, which is a huge design problem. Unlikely unless GPU mining for scrypt is very profitable.

This also makes Scrypt far more energy intensive for the same amount of useful hashing, but the network adapts as it requires far less hashes to solve problems (Difficulty number)

Which is greener? By far ASIC mining, it's power usage is tiny compared to performance, 4500MH for 4.5w vs 275MH for 100w.

But again, the network balances.


The network adapts by changing the difficulty level, which means adjusting the chance that any single hash computation is accepted as finding the next block. If the hash rate for the network goes down, the difficulty decreases which means any single hash calculation has a greater chance of finding a block. If the hash rate of the network goes up, the difficulty goes up and the lower chance there is of a single hash calculation finding a block. The system is designed this way so that, no matter how many hashers there are in the network, a block is going to be found every X minutes on average. (The value of X depends on the fixed design of the currency but is hard-coded so doesn't fluctuate once the design is fixed.)

Said another way, a hash is accepted as finding a block if the result of the hash is less than some value Y. What happens by adjusting the difficulty is that this Y value goes up or down. So more hashes on the network increases the difficulty and lowers Y. Fewer hashes decreases the difficulty and raises Y.

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