Mining past 95% probability... at what point should I suspect a problem?

[Zerbie]

I set up a new mining computer Thursday night that has a hash rate of 640000 khash/s.  I also have my main system mining at a rate of 320000 khash/s.  Based on the probabilities provided via http://www.alloscomp.com/bitcoin/calculator.php, on average, I should see a block every 1.21 days (assuming 900 Mhash/s), and I should have a 95% chance of seeing a block in 3.625 days.  Since I've yet to see a block on either of these systems I'm beginning to worry that something has been hacked or there is some other problem. 

At what point should I assume there is a problem and clean off the systems and re-start?  Based on the 50% time, I estimate a 99% chance for 6 days of mining, which would be Wednesday morning.  The odds of 6 days of mining at 900 Mhash/s without a block is 1/100.

Anyone have any ideas on what to look for regarding a hack?

[Garrett Burgwardt]

Some people seem to just be incredibly unlucky in terms of mining. I personally have 2 5870s and a 5770 hashing almost 24/7 and I went a week or more without a block, and just today found two apparently. It's all luck, and some people are just unlucky

Don't worry, and if you get tired of no results try joining a mining pool 

[Raulo]

3 possible ways:
- join the mining pool and see if shares are accepted
- run your client on testnet
- modify the miner to print more debugging stuff. Increasing target (lowering difficulty) also can help spot the problems.

[Mahkul]

I set up a new mining computer Thursday night that has a hash rate of 640000 khash/s.  I also have my main system mining at a rate of 320000 khash/s.  Based on the probabilities provided via http://www.alloscomp.com/bitcoin/calculator.php, on average, I should see a block every 1.21 days (assuming 900 Mhash/s), and I should have a 95% chance of seeing a block in 3.625 days.  Since I've yet to see a block on either of these systems I'm beginning to worry that something has been hacked or there is some other problem. 

At what point should I assume there is a problem and clean off the systems and re-start?  Based on the 50% time, I estimate a 99% chance for 6 days of mining, which would be Wednesday morning.  The odds of 6 days of mining at 900 Mhash/s without a block is 1/100.

Anyone have any ideas on what to look for regarding a hack?

Don't worry man, I know the feeling and it is perfectly normal. The same way sometimes you may see many blocks generated within a short period of time, sometimes you won't see any of them for a while (even above 95% - I have experienced that myself a few times).

Still, maybe there is something wrong with your miners.

[Zerbie]

3 possible ways:
- join the mining pool and see if shares are accepted
- run your client on testnet
- modify the miner to print more debugging stuff. Increasing target (lowering difficulty) also can help spot the problems.

Can you link me to the testnet and debugging documentation or thread?

Thanks!

[Raulo]

Can you link me to the testnet and debugging documentation or thread?
Thanks!

Testnet:
https://www.bitcoin.org/smf/index.php?topic=1509.0

You simply run your bitcoin with -testnet flag and connect with your miner as usual. Current difficulty on testnet is 186 so it still takes a while to mine on testnet.

For debugging, consult individual miners threads.

[左]

I can generate something like ~500 khash/s (depending on how much I'm using the computer), using either a miner, or the default client.

The website given earlier suggests it'll take me at least 1791 days to have a 50% chance of getting a block. Being part of a mining coop has generated some small amounts, but I don't think it's likely to be worth it at all.

Thoughts

[davout]

Testnet has been reset in the github source tree, in other words, if you compile from source you'll have a testnet with ~1 diff. Should be much easier to test

[Littleshop]

Any update?  Did you get a block?

[c_anderson]

I think you may be misreading your hash/sec number. If gethashespersec returns 640000, you aren't getting "640000 khash/s". You are getting 640000 hps = 640 khps (640000/1000).

In order to reach 95% probability, you'll need to run for 8483 days.  :/

[caston]

Try mining on a 486DX next to your high end mining rig. If your expensive rig is so unlucky maybe the 486 will do better.

[grue]

I think you may be misreading your hash/sec number. If gethashespersec returns 640000, you aren't getting "640000 khash/s". You are getting 640000 hps = 640 khps (640000/1000).

In order to reach 95% probability, you'll need to run for 8483 days.  :/

this

Unless you have a very high-end video card, you won't be able to get that hash rate.