37% difficulty increase (55590 to 76193)

[Transisto]

Difficulty History
Q: Is there a replacement for the dead link . "http://nullvoid.org/bitcoin/difficultiez.php" ?

I bet it will drop once summer kicks in, 

[khal]

Here : http://blockexplorer.com/q/nethash

[theGECK]

Just a bit of information I came up with while talking with a friend of mine today. Based on the last blocks found by slush's pool that fit on my screen at one time (I think it was 15), the value of a share was .0006 BTC. (Since the score based model evens out over time to match the share based, I think it's fine to talk about the value of a share.) That means that the new value of a share will be about .000378 BTC.

My miner does 300-310Mhash/s, and found 469 shares in 2 hours, which is average for me. This is 3-4 shares per minute. At 100 Mhash/s, you should expect 1 share/min. You can use this as a way to see how many BTC you can expect to mine. Here's the table I made to share with my friend, hope I did the math right, and hopefully somebody can use this to see if it's worth it to them to mine.

Mhash/s      Estimated Hourly Payout      Estimated Average Daily Payout
10               0.002268                          0.054432
20               0.004536                          0.108864
100             0.02268                            0.54432
300             0.06804                            1.63296
500             0.1134                              2.7216

[os008]

Mhash/s      Estimated Hourly Payout      Estimated Average Daily Payout
300             0.06804                            1.63296

I think something is wrong here. I calculated and tested on the course of a week; my average was 0.2 BTC per hour, with the new difficulty it's 0.145 per hour. Your averages are too low for some reason.

[theGECK]

Mhash/s      Estimated Hourly Payout      Estimated Average Daily Payout
300             0.06804                            1.63296

I think something is wrong here. I calculated and tested on the course of a week; my average was 0.2 BTC per hour, with the new difficulty it's 0.145 per hour. Your averages are too low for some reason.

I was thinking something was off, but the numbers bore out. Maybe I was just at an unlucky patch when I took my readings. My average was .2/hour before the difficulty change.

So, I'm going to do the math out here, and maybe we can see where I went wrong.

Statistics taken from mining.bitcoin.cz.

Blocks 1841-1865 = 24 blocks = 1200 BTC payout
Total shares of those blocks = 1,989,659 shares
BTC/share = 6.0311842381031121413267298567242e-4, or .0006/share (rounded)

So far it seems that the value is holding the same, and there isn't enough blocks with the new difficulty to throw the averages off yet. Or maybe the average will always be the same, but the rate that shares will be found by the same miner will be slower.

Current Round Duration: 0:23:18
Shares Found: 105
Hash rate: 310Mhash/s.

So, If I multiply 105 by 3, I should get a number that is close to what I should expect each hour at the current difficulty.

This is where my problem was - I used the rate of share discovery from a block with the new difficulty to figure out averages in the old difficulty. Since the share rate is slower with the new difficulty, the payout looks lower.

So, my payout previously was about .2/hour. With a 37% difficulty increase I expect it to be .126/hour. With that (rounded to 4 decimals)...

10Mhash/s - .0042/hour - .1008/day
20Mhash/s -  .0084/hour - .2016/day
100Mhash/s - .042/hour - 1.008/day
300Mhahs/s - .126/hour - 3.024/day
500Mhahs/s - .21/hour - 5.041/day

That looks more accurate to me. Same with everybody else?

[BitLex]

why so complicated?

i would say, it isn't a good idea anyway to base your average expectations on the number of blocks a given pool found a few days/weeks back, but rather on your hashrate, the pools comissions and the current difficulty.

at 10Mhash/s you'll need an average of 9090.5hours to create a block,
let's just say the pool takes 3% and due to network-overhead/-connectivity and invalid or stale hashes you lose another 2%,
then you'll need 9090.5hours to create 47.5BTC on the pool, that's what you can and should expect on average.

10M: 47.5/9090.5 = 0.00522BTC/hour or 0.125BTC/day

[os008]

I simply calculate it by multiplying the share price, by the number of shares per hour i submit on average (doesn't change much).

0.00058 * 250 = 0.148 BTC/hour

The previous number was very accurate for me using that method, and this number is accurate so far, also.

[theGECK]

I just remember that everything goes in a cycle, and whatever spikes will drop. The difficulty spiked, so it will drop eventually. And I'm not mining for the money, it's just a nice benefit.

[theGECK]

More (probable) math problems a friend and I are trying to do.

Looking at the 5770, you have a 156.83 Mhash/s, and based on the Mhash/w rate, that's .688705234 watts per Mhash. So, this is what the friend emailed to me:

So in a second, you're using 156.83*.688705234 Watts. That's 108.009642 Watts per second, or 388834.711 Watts per hour. Divided by 1000 will give you the kwh, of 388.834711 kwh. At $.11/kwh, that would be $43.22/hour, and you would expect 1.5 BTC each day at the current difficulty. How do people make money with this?

Clearly this isn't right, but I'm not sure how to calculate actual video card power usage, but where in the above are we off?

[AmpEater]

More (probable) math problems a friend and I are trying to do.

Looking at the 5770, you have a 156.83 Mhash/s, and based on the Mhash/w rate, that's .688705234 watts per Mhash. So, this is what the friend emailed to me:

So in a second, you're using 156.83*.688705234 Watts. That's 108.009642 Watts per second, or 388834.711 Watts per hour. Divided by 1000 will give you the kwh, of 388.834711 kwh. At $.11/kwh, that would be $43.22/hour, and you would expect 1.5 BTC each day at the current difficulty. How do people make money with this?

So, I'm not sure how to calculate actual video card power usage, but where in the above are we off?

A watt is a joule per second.

It's not 108 watts per second, its just 108 watts.  108 watts for ten hours is about 1kwh.

[jkminkov]

More (probable) math problems a friend and I are trying to do.

Looking at the 5770, you have a 156.83 Mhash/s, and based on the Mhash/w rate, that's .688705234 watts per Mhash. So, this is what the friend emailed to me:

So in a second, you're using 156.83*.688705234 Watts. That's 108.009642 Watts per second, or 388834.711 Watts per hour. Divided by 1000 will give you the kwh, of 388.834711 kwh. At $.11/kwh, that would be $43.22/hour, and you would expect 1.5 BTC each day at the current difficulty. How do people make money with this?

So, I'm not sure how to calculate actual video card power usage, but where in the above are we off?

with $43.22/hour, you'll end up with $29,000 electricity bill to pay, fortunately for your wallet, copper wires will melt in the very first 2 minutes

[theGECK]

More (probable) math problems a friend and I are trying to do.

Looking at the 5770, you have a 156.83 Mhash/s, and based on the Mhash/w rate, that's .688705234 watts per Mhash. So, this is what the friend emailed to me:

So in a second, you're using 156.83*.688705234 Watts. That's 108.009642 Watts per second, or 388834.711 Watts per hour. Divided by 1000 will give you the kwh, of 388.834711 kwh. At $.11/kwh, that would be $43.22/hour, and you would expect 1.5 BTC each day at the current difficulty. How do people make money with this?

So, I'm not sure how to calculate actual video card power usage, but where in the above are we off?

A watt is a joule per second.

It's not 108 watts per second, its just 108 watts.  108 watts for ten hours is about 1kwh.

So, it's sounding like you are saying that a watt is a unit that's already been converted to an hour. So, if I had a 1000w power supply running at full capacity, it would be using 1kwh.

[error]

Your friend used "watts per second" where he should have used "watts per hour". As a result his numbers are far, far off.

[theGECK]

I just realized how dumb I was - kwh would be kilowatts * hours. Or hours * watts / 1000. Wow - it must be Friday.

[Quantumboredom]

Your friend used "watts per second" where he should have used "watts per hour". As a result his numbers are far, far off.

Watts per hour also does not make sense. As others have noted watts are a measure of energy per time already, so "watts per <insert time unit here>" would be some funky kind of energy acceleration measure that nobody uses .

It really is as simple as:
100 W = 0.1 kW

If we use 0.1 kW for 5 hours we would get:
0.1 kW * 5 h = 0.5 kWh

Don't feel bad though, I've even seen electricians getting confused by this

[compro01]

So in a second, you're using 156.83*.688705234 Watts. That's 108.009642 Watts per second, or 388834.711 Watts per hour. Divided by 1000 will give you the kwh, of 388.834711 kwh. At $.11/kwh, that would be $43.22/hour, and you would expect 1.5 BTC each day at the current difficulty. How do people make money with this?

Clearly this isn't right, but I'm not sure how to calculate actual video card power usage, but where in the above are we off?

take your power usage and multiply by time.

for example, my computer, running both GPU (8800GTS) and CPU (core2 duo e6850) miners, draws 270 watts (2.25 amps at 120 volts)

270W*24 hours= 6.48 kilowatt-hours (not kilowatts per hour, it's a draw of 1 kilowatt for an hour or 500W for 2 hours or anything that multiplies out to that same product) per day or 194.4 kilowatt-hours per month.  alternatively, 23.3 megajoules and 700 megajoules if you want the actual SI units.

at current electricity rates here (9 cents per KW-hr) that's $17.50/month.

ordinarily, not profitable for me (prior to the difficulty spike, i estimated i was mining about 12 BTC/month in the deepbit pool), but;

a. 170W of that is idle operation, as this machine is also a web server, so it already needs to be running 24x7, so it really only costs me an extra $6.50 per month.
b. I don't even pay that as my electricity is included in my rent.

[Jim Hyslop]

I bet it will drop once summer kicks in, 

Or it might pick up in Australia....

[CCCMikey]

Or it might pick up in Australia....

Not for me ;-)

http://www.reddit.com/r/Bitcoin/comments/fxrse/generating_bitcoins_now_financially_impractical/

Unless I have the maths wrong too, I'll be waiting ten years...

[CCCMikey]

My GPU is not supported in my media centre PC so I could not try.

How many khash/sec do you get on average from a good GPU, and at what wattage?

[LMGTFY]

I'm not sure how GPUs perform in comparison - but would need to be about 8 times better than one 2GHz CPU @ 30 watts to be feasible.

Dude should actually figure out how much better GPU's perform in comparison... It is way better than that.

Two AMD Opteron 6128s will get you 32.4 Mhash/s: that's the best result for CPUs listed on the wiki's mining hardware comparison list. One AMD Phenom II X6 1055T will get you 15.84 Mhash/s.  In contrast, 1 AMD 5870 GPU will easily get you 324 Mhash/s - 10x what the 2 6128s would deliver, and 20x what 1 1055T delivers. A 5870 is probably considered entry-level now for GPU mining - a 5970 will be almost twice as fast. And that's before you consider that it's relatively easy to use more than one GPU.