you'll average a block every 29 hours.
Nope. 2**32*244139/7567e6/3600 = a block every ~38 hours. |
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Yes, they do indeed draw power from the PCIe connector, even though they have additional power connectors.
He is referring to the ATX power spec. 12v power for PCIe slots is provided by only two pins in the ATX power connector, rated for 6 amps each. He was pulling 7.4 amps over each pin, which was melting the shroud and likely caused permanent damage to his motherboard. It probably would have started a fire eventually if he hadn't been actively watching it.
His solution was to bypass the ATX plug (and motherboard) entirely by spicing his PCIe extenders to accept power directly from the power supply.
I understand what he did. What I don't understand is why most people are NOT seeing such issues. Because few people are running 4x5970 or 4x6990 with the PCIe slots power entirely coming from the 24-pin ATX connector. I spliced my PCIe extenders. ArtForz is doing something similar. foxmulder has extra power connectors on his SR-2. Etc. You have to understand that specifically the 5970 and 6990 are the cards with the highest current consumption on the slot (I measured 4.1-4.3A at 12V). Most other cards have 2/3rd or less the consumption (eg. the 5870 only draws 3.2A at 12V from the slot). |
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BTW, Syke, I couldn't reproduce your numbers with Phoenix. I obtained 664 Mhash/s, which is slightly lower than reeses.
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Exactly  More seriously, regardless of the BTC/USD exchange rate, my miner still produces 6.3% more Bitcoins than the 2nd fastest miner, so it makes sense for my price to be relative to the Bitcoin instead of the Dollar. (Feels weird to say "the Bitcoin"). |
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Current price is 7.92 BTC per Ghash/s per day.
I have made my model more flexible so you can rent for any number of days, from 1 to 365 days. For example you can rent 10 Ghash/s for just 1 day, if you want so.
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A micronation is an entity that claims to be independent, but is not recognized by other governments, for example: Sealand, Empire of Atlantium, Naminara, Kingdom of Lovely, etc. Bitcoin obviously fits the philosophy of independence of micronation founders. We could attempt to entice some of them to adopt or promote Bitcoin somehow, if only as a publicity stunt. A micronation could: - come up with a customized physical representation of Bitcoin (the same way each European country customize one of the sides of Euro coins)
- declare Bitcoin as its official currency
- peg their currency to Bitcoin
- etc
Relevant links: http://en.wikipedia.org/wiki/List_of_micronation_currencieshttp://en.wikipedia.org/wiki/List_of_micronationshttp://en.wikipedia.org/wiki/Micro-nationIf this is successful, the next step would be to market Bitcoin to microstates which are, contrary to micronations, formally recognized (Liechtenstein, Monaco, etc). But that is, of course, much harder |
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I doubt SHA256 will be broken (and not just one collision found!) any time soon, but if it was to happen, don't underestimate the consequences on bitcoin, as anyone could create a longer block chain "from scratch", thus totally destroy the current one.
No, because there are checkpoints in the current chain (hardcoded blocks). So it would be impossible to rewrite history before the last checkpoint. What a preimage attack on SHA-256 would allow, however, is the ability to grow the chain very quickly, as if one had a lot of computing power. This would allow double-spending, etc. |
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Q: the difference between a slot machine and a mining rig?
A: With the slot machine, you put $1 in, and it gives you $0.90 back. With a mining rig, it gives you $1 back, and again, and again, and again...
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I'm sorry, but your service is not the cheapest. Our 800 GH/s contract is $400/mo, which is approximately 278€. Please update your post accordingly.
800 GHash/s ! I am buying immediately :-) s/G/M/ |
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And I would much rather buy in BTC than USD! We were destined to do business together  Unfortunately I am in California. What price would you agree on then? 140 BTC? |
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AFAIK you are the first large (~$10M revenu/year) computer hardware store to accept Bitcoin. Very cool.
I bought an HD 6990 for $720 today from Tigerdirect. I think you should match their price. The MtGox avg was ~$5.60/BTC over the past 3 hours, so I will consider buying one from you for 130 BTC, including UPS ground shipping & taxes. Ok?
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Processing power is required to move data around and do instructions, those instructions and data being moved around are done in the GPU... now let us BOTH think what happens when your CPU can't keep up with the GPU in some (i said some) respect? Obviously the GPU is and will always be better, BUT it doesn't mean you put a $10 single core with a $700 GFX and expect perfect results.
Yes, perfect results. All my 4 x 5970 rigs have a low-end single-core $30 Sempron processor and run at exactly the expected speed. You need to get a sense of the workload involved, and understand numbers reported by your system monitoring tools. We are talking about a few hundred kB/s exchanged on the PCIe links. And the CPU waking up every 100ms or so to send new work items to the GPUs. It is peanuts. All of that is orders of magnitude below what a single Sempron core is capable of. |
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It seems impossible to me to use floating point to emulate an integer right rotate.
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They are wrong about the threads operating on the same data. A naive reader skimming over the code may think most of the data is the same, but the 32-bit nonce is unique for each thread, which leads to different SHA-256 intermediate hash values (A-H) being manipulated by each thread. Re: enterprise prices - it is truly market segmentation, whether you want to believe it or not. The 2 largest and public disk reliability studies ever performed were made by Google and CMU. They reveal interesting findings. In particular, contrary to what you think, the CMU one reported no statistical differences between the failure rate of SCSI vs SATA drives on a population of 100k+ drives: * Failure Trends in a Large Disk Drive Population - Google* Disk failures in the real world: What does an MTTF of 1,000,000 hours mean to you? - CMUWhich makes sense when you think about it. Commodity drives are produced in such a high volume that it is in the manufacturer's interest to make them as reliable as possible, because a small improvement in reliability drastically reduces the number of warranty claims. This is just some food for thoughts... You should trust more of the people here. The Bitcoin community is full of smart folks. Open source has produced some of the highest-quality software in the world: Linux, Apache, etc. A miner is also just a few hundreds lines of code. It is not the complex, hard-to-optimize software beast that you may imagine. |
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They are lying to you ("no parallelism", "+350%", ha!) You must have contacted sleazy consulting houses that will say anything to steal money from you :-)
It takes about 3200 operations to execute the SHA-256 compression function without a native integer right rotate instruction (ie. Nvidia).
One Bitcoin hash is 2 calls to the compression function.
Therefore a Tesla M2050 with 448 ALUs at 1150MHz can only execute 448*1150e6/3200/2 = 80.5 Mhash/s which is the theoretical number I gave earlier.
The best you can do is shave a few ops from these 3200 (such as precomputing some of the SHA-256 shuffling steps, which I am planning to implement in my ATI miner), but that would lead to only a few percentage points of perf improvement...
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High? Yeah... ok. Tell me where you can find a brand-new 5970 for less than $650-$700. They are better miners, and they are becoming very scarce now. There are many sites, such as Amazon, that are actually charging $800+ due to their limited availability. But sure, let me go ahead and spend like $175 more to buy a 6990 from Newegg (the total price will be around $800 after taxes!).
Or maybe you didn't notice that this card is brand-new? Maybe a used card could be had for less or something, but I'm not gonna mess around with crap like that.
I agree with eck, that is a high price. You can find 6990s for $710 if you buy out-of-state to avoid the sales tax. That's only 16% higher than what you paid for the 5970, except the 6990 is approximately 20-25% faster. So a 6990 would have offered you more bang for the buck... |
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Why does ATI have an advantage?
Because of this: Why are ATI GPUs faster than Nvidia GPUs?xenon481: it is not a matter of floating point vs integer. When comparing current generation GPUs, Nvidia does not have a floating point advantage anymore over ATI. Not even with the Tesla 2000 series which can do 1 DP op every 2 cycles (Tesla C2050 = 515 DP GFLOPS vs. HD 6970 = 676 DP GFLOPS). |
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At what point in the podcast does Leo smash bitcoin?
It is at 47:25. The host Leo seems to actually like Bitcoin (he was one of the hosts in that great Security Now show about Bitcoin.) Instead, he criticizes the cash/Bitcoin exchange markets which, he thinks, are mostly used for money laundering. Here is the actual quote (the context is within a segment of the episode where they are talking about alternative currency / money transfer sites like WebMoney, Liberty Reserve, and how they are used by crooks to sell illegal software and services): You know Bitcoin, which is very interesting, we did a whole show on Bitcoin at Security Now.
I think, really, because you can generate these Bitcoins on your Mac or any computer with spare cycles.
And then there is a a market for Bitcoin in cash.
And the only reason I could think of why that would be is because that's a great way to launder money, you know.
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