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I wrote a tool that compares the order books between MtGox and Tradehill, just to see how much USD and BTC you would really need on deposit to make a reasonable profit.  I used Tradehill and MtGox because they were the only 'live' exchanges with enough volume to make this even worth considering.  What I found agrees with what other people have already said in this thread:  arbitrage exists, but it's probably not worth chasing because of the large deposits required to generate profits.  But I thought it might interest people to see some actual numbers.  Here is an example from around 22:30 EDT today:

BUY TRADEHILL, SELL MTGOX

   MtGox Sell Order: 183.5775 @ 18
Tradehill Buy Order: 183.5775 @ 17.5
========================================================
         Requires: $3212.60625 on Tradehill, 183.5775 BTC on MtGox
         Sold for: $3339.477523
           Profit: $ 126.871273

Note that because moving USD around is very slow, you would actually need a lot more of it in your exchange account than these figures show, assuming you want to do more than one transaction like this per day.  You can move the BTC back and forth in about an hour to restore your balances, but not so with the USD.

I was talking about this massive hashing increase with some friends and someone mentioned that someone he knows, who runs computing for a major genetics research facility with ~3000 4x GPU servers, decided to use their idle cycles to mine and brought them online today.  Totally unsubstantiated, and hard to believe you could get away with that for very long, considering the power draw, but who knows.

If there is some other thread you can point me to where all of this is already covered that would be appreciated.

I originally just wanted to know if there was something going on with reporting, since there have been a lot of those kinds of problems in the last few days due to new servers coming online, and that round was very unusual.

I am now curious as to the statistics at work here.  Most of my analysis, such as it is, is based on the Bitcoin Generation Calculator.  I am assuming that the formula used there to calculate 50% / Average / 95% times to solve a block is valid, because the calculator does seem to predict fairly well how many BTC I will receive in a given time frame at a particular hash rate and difficulty.  I will admit to being a little confused here already, though, because it seems like the numbers for 50% and Average should be the same.  I clearly don't understand the finer points that lead to this distinction, or why my assertion that a 3.5 hour round @ 1.5TH/s is extremely unlikely using those numbers is wrong.  I am trying to learn the math though, so any links are definitely appreciated.  PM me if you don't want to clutter up this thread any further.  Thanks for your help.

As I understand it other pools solving blocks doesn't affect our chances of solving a block at all, it is random chance when we hit one.  Having 1500GH/s just means we buy 1.5 trillion lottery tickets every second.  Sure we start using a new block header for hashes every time anyone solves a block, but that doesn't change the odds.  According to my limited understanding we have a 95% chance of finding a block within 1.5 hours at that hash rate.  A 2 hour round is an anomaly, a 3.5 hour round seems damn near impossible.  Not actually impossible, but so unlikely as to make me wonder if something else is going on.  It is certainly possible I'm misunderstanding things, I am no statistical genius.  Please educate me.

Is there currently a reporting problem?  I see this:

9,553 workers at 1,536.46 GH/s
Round Time   3:36:20      Round Shares   4577435

Statistically speaking this is extremely improbable.  Is all the server shuffling creating problems for the website such that it doesn't really know when a block was found?  Or are we really just winning the anti-lottery?

Same here.  Miners going down repeatedly all day, often requiring manual restarts.  Making me sad

Would be nice if Mt.Gox actually put up a message on their own website.  It's pretty lame that we have to find out about these problems by reading these forums or reddit.

EDIT:  There is now a message about the withdrawal problem on the Mt.Gox homepage.  Thanks Mt.Gox!

Seriously though, they're built with quality components and have good airflow, so as long as you don't do anything retarded like block the intakes or run it in a closet you'll be fine.

Hi all.  I'm building and selling mining rigs for bitcoins.  These are great starter rigs:

546MH/s with the stock configuration -- earns about 1BTC per day at current difficulty
Low power CPU and high-quality power supply lower your electricity costs

Some specs:
2 AMD Radeon 5830 cards
AMD Sempron 140 2.7GHz Processor
80GB disk

The price in bitcoins fluctuates with the USD exchange rate, but they are roughly 27 BTC.
I'll also accept dollars if you prefer.

You can buy them through my website at http://bitminer.us/
There is a lot more information there.

Feel free to post questions here, or mail me directly through the website.

EDIT:  I'm out of stock, but I'll still take pre-orders if you're willing to wait a week or so while I source more parts.

Thanks Nuke.  The motherboard is pretty nice, it's an MSI 870A-G54.  You can find more info on it here:  http://www.msi.com/product/mb/870A-G54.html

Shipping to Europe is possible but it is expensive.  For instance, about 150 USD to get it to Berlin in 5 business days.

Core 875, Memory 300.    273MH/s each

Hi all.  I'm offering lower-end mining rigs for sale here:

http://bitminer.us/

I figured Bitcoin Rigs could use a little competition 

These are dual 5830 rigs that get 546MH/s, built with good quality components.  They are intended for people without a lot of tech skills who want to try out mining but don't want to spend a grand for less hashes.  These include custom monitoring scripts that will text you if your miner goes down, assuming the machine is still running and connected to the net.

The site is brand new so if you find problems with it please let me know.  Of course Bitcoin is accepted for purchase, or PayPal if you're more into that.

I'm currently accepting pre-orders because I'm waiting on some parts (expected on Wednesday 6/8).  Should be shipping some by Thursday.

I'm talking more about a system that's not on the pool server or even in the same datacenter, running nagios or some other monitoring software that allows it to make requests periodically to the pool to make sure the system is fully functional.  It is not good if you have the pool server also doing the monitoring, because when it goes down it probably won't be able to send the alert  

I have done a lot datacenter and sysadmin work and systems going down is a fact of life.  But any organization that has systems where finance is involved sets up a monitoring system that will alert the right people when things go offline.  I like your pool best and I would really like it to stay up.  I would be happy to volunteer time to set up monitoring for you or provide advice in that area. PM me if you are interested.