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1  Bitcoin / Bitcoin Discussion / So I'm speaking at DEFCON 19 about bitcoin... on: June 18, 2011, 07:16:10 PM
That's right, I just found I got accepted to speak at DEFCON 19 about bitcoin.

I'm open for input, giving a 20 minute talk.
2  Bitcoin / Mining / Re: Miner Meets Voldemort on: June 18, 2011, 07:07:47 PM
Am I the only one who questions the veracity of this story?

I don't think a 1200W power supply is going to literally explode a hard drive.

Pics or it didn't happen.
3  Bitcoin / Mining / Re: Someone just fired up some serious hashing power. on: June 17, 2011, 05:54:14 AM
My guess? Someone's ASIC based mining-farm just came online bit by bit.
4  Bitcoin / Mining / Re: Mining rigs "after Bitcoin" on: June 17, 2011, 05:45:34 AM
My rigs will be used to drive personal video wall(s)

Got a big lot of 30 LCD monitors in january and I've been set on making a video wall ever since.
5  Bitcoin / Mining / Re: 8 HD 5770 GPUs on a Big Bang Marshal? on: June 17, 2011, 02:10:07 AM
You're going to need about 2 * 1200 watt gold PSUs for that beast imho. So that's at least $500 USD.

for 8 5770s? You're crazy. You don't need 2400 watts to power 8 5870s. A full system with CF 5770s was measured by anandtech as pulling 390W from the wall. Even ignoring the system overhead, 390W * 4 = 1560W. Many people have reported their AX1200s as being able to do that without too much fuss. Not a cheap PSU by any stretch of the imagination, but certainly not $500. More like $250.

Anyway, would the big bang marshal be capable of supporting all 8 of these? The main reason I'm so attracted to making an 8-GPU system is because is because repurposing it is an easy way to drive a 12-16 monitor video wall without messing with (the highly buggy) xdmx.

Again, you run the potential risk of burning out the mobo if you don't provide power bypass for some PCIE slots. They will also need to be single slot 5770s or else you will need to use extenders anyway. If they are not single slot you will need some sort of custom built rig to hold all the cards in place as well. Some things to consider.

Also I still don't have confirmation one way or another, but some users report issues with getting windows to recognize 5+ physical video cards. If you planned on linux anyway not as much an issue.

Just because people say that a 1200 can handle 1560 watts.. doesn't mean it's a smart idea.

I like to get more than 6 months out of my $200 PSUs anyways... so I keep them all at 50% load.

A few things of note

1) 1560Watts is Wall power. PSUs are rated to deliver their labelled rating *to the system* (this is after AC/DC conversion). 1560watts (which is higher than the real amount used, I just used it for ease of demonstration) from the wall is ~1300Watts to the system, these are non-underclocked cards to boot, so the real deal will definitely use less power. But regardless, AX1200s are overdesigned to be able to produce that. Yes it is overloading, but if you really really worry about that, drop a $15 cx430 in the mix, solved.

2) lol @ 50% load. That's potentially the most cost inefficient thing I can imagine. Not only are quality PSUs designed to produce 100% of their labelled power (well read the label, 12v will be slightly lower than total), they are designed to do it continuously. That is 24/7/365. That's why a quality PSU comes with a 5 YEAR warranty. The manufacturer knows that they won't have to make good on very many of those warranty claiicms.

Why not underclock your CPU on your main computer to half clocks so it will last longer? Makes about as much sense to me.

I'm fairly sure power supplies are at peak efficiency operating at 50-75% load, but don't suffer major performance loss above that, only below. I know they are designed to operate at full load 24/7/365 though, the first thing to fail will probably be an electrolytic cap and they're cause for failure is rapid discharging or overvoltage.
6  Bitcoin / Mining / Re: 8 HD 5770 GPUs on a Big Bang Marshal? on: June 17, 2011, 12:15:55 AM
I'm curious what calculations you used to determine that you could break even or make a profit with such a setup. What rate of difficulty increase did you assume, and over what period?

I assumed initial depreciation of 0.15*base price for unboxing, then 0.003*base per day thereafter, with mining profitability at a conservative 1.3cent-day per megahash (including electric costs). Giving the profit function including hardware resale where x is in days of (22.1*x)+(1800*(0.997^x))-2070

This gives 16 days in the red assuming hardware liquidation.

Without liquidation, ((22.1*x)-1800) which comes to 81 days.

We're currently at 2.2cent-days per megahash, so this is very conservative calculation wise on mining profits, I'm assuming the worst  Huh
7  Bitcoin / Mining / Re: 8 HD 5770 GPUs on a Big Bang Marshal? on: June 16, 2011, 11:31:49 PM
bcpokey, people don't have the luxury of building 1.73Mhash/$1 systems anymore.  It can't be done.

My most efficient build was right up there, yay for the microcenter markdown bin. 600mhash for $344

Anyway, would the big bang marshal be capable of supporting all 8 of these? The main reason I'm so attracted to making an 8-GPU system is because is because repurposing it is an easy way to drive a 12-16 monitor video wall without messing with (the highly buggy) xdmx.

Also WTF two 1200W psus!? I thought one would do fine!
8  Bitcoin / Mining / 8 HD 5770 GPUs on a Big Bang Marshal? on: June 16, 2011, 09:22:11 PM
Topic says it all. Will it work under linux?

I put together a hypothetical parts list that came to about $1800 and 1.7ghash/sec on a single box based around this $400 monstrosity of a mobo.
9  Bitcoin / Mining / Re: I bet there's a guy . . . on: June 14, 2011, 02:20:56 AM
i find it hard to believe that you don't feel bad about losing 300,000$.

Would you feel bad about using toilet paper to wipe your ass if it was deemed a rare commodity 20 years later due to all the forests being cut down?

That's how I feel because there's no way to get it back.
Besides, that long ago people were using thousands of BTC for fun on bitcoin blackjack sites, or even that famous 10k pizza. It was more like a fun game and less of an actual currency.

Data recovery anyone? It's possible you may still be able to get them.
10  Other / Obsolete (selling) / Re: Invite to private torrent site .3BTC on: June 11, 2011, 08:39:20 PM
Is this either "PTP" or "TVT"? I'm already in both, but if its something different I might be interested.
11  Bitcoin / Mining / Re: The guy who sustained permanent brain damage tells his story on: June 11, 2011, 08:30:47 PM
They rushed me to the ER, and at this point I was barely conscious so I donít remember everything, but they put bags of ice on me and made me drink tons of liquids
What, the ER was out of IV's?

That is standard treatment for hyperthermia...

Also I seriously thought this guy was trolling when I first saw the story on /g/.
12  Bitcoin / Mining support / Re: How to build your own power supply? on: June 11, 2011, 05:14:01 AM
I am considering spending almost $1,000 on 3-4 gold rated PSUs.

Seems to me they are little more than transformers.

If I could purchase 4*$30 PSUs simply to run the motherboard/cpu power... could I note create a massive single 12 volt rail that distributes power to say 30-40 video cards via pcie connectors at once?

I guess it would really suck if THAT power supply broke down... but still - anybody tried it or similar?

The PCIe bus spec only allows 30watts per slot, thats why most higher end video cards have external power connectors on them.
Sure, you probably could bridge together enough cheap power supplies to power all those cards. Or, come up with one really big 12V power supply capable of handling 100's of amps.

The problem with lower quality power supplies is the power you will get out of it then will have ripple, and inconsistent voltage regulation which will make bridging more then a few cheap supplies together difficult, since they will not supply current evenly across all the supplies.

A single very large supply has the other problem that it requires very thick cables, or copper buss bars to distribute all that power to the cards.  Ciopper buss bars carrying hundreds of amps are dangerous at almost any voltage, and require regular maintenance to maintain good connections to prevent excessive heating of the buss or connectors.

I wouldnt risk thousands of dollars in GPU's connected to a makeshift 12V power supply, it's just not worth it.

Actually, powering ~20 GPUs off something like this might be quite a good solution for large mining farms:

It compares quite well to a computer PSU, and would cut costs a good bit for large scale miners.
--Efficiency of Whole Body: ≥86%. Source Voltage Regulation:
--Voltage-stabilizing ≤0.2%. Load Regulation: ≤2%; Ripple Voltage: ≤4%
13  Bitcoin / Mining / Re: Botnets on: June 11, 2011, 05:07:12 AM
If we assume the average computer in the BredoLab botnet (largest ever known) has a time-averaged hashing capacity of 10mhash/sec (very rough number considering the high end hardware/gaming market is a few percent, likely has an inverse correlation with botnet membership, and most zombies run at less than 100% uptime), then a botnet as a whole of that size could do around 300thash/sec, increasing hashing power by 5,000% and netting the botnet owner somewhere in the neighborhood of $11 million a day. (wrongly assuming this has NO effect on the exchange or difficulty rate)

This of course would give said botmaster a stranglehold on the bitcoin economy, he could monopolize generation by producing 98% of all blocks, he could hoard his coins to drive up prices.

The one thing he couldn't do is sell a large lot of them without crashing the market. Realistically moving anything upwards of a quarter million a day is going to have a large deflationary impact on the market in short order.

Feel free to check my math, but even a fairly small botnet could wreak havoc.
14  Bitcoin / Mining / Re: Hardware for cheap through liquidation auctions? on: June 11, 2011, 04:55:40 AM
I got thousands (to tens of thousands) in hardware for a couple hundred when my local circuit city liquidated a couple years back. Mind you most of this stuff was stuff that wasn't selling otherwise, high current 12V PSUs, huge runs of CAT5 or RG6, cash registers and other POS stuff, etc

The day after it closed they invited me in to take whatever I wanted free before the garbage crew came in, I ended up with a ton (actually a few tons) of random electrical crap, some of which I sold as scrap.
15  Bitcoin / Mining support / Re: How to build your own power supply? on: June 11, 2011, 04:27:36 AM
The real answer in electrical safety is that it takes a combination of sufficiently high voltage, current, and the proper waveform to kill you. 240V mains is nearly ideal for this.

A van-de-graff generator can produce very high voltages, and high current pulses, but has a very low RMS power and averaged current, and is thus safe.

5V USB or a car battery can produce a lot of current with a steady DC waveform, but lack sufficient voltage to produce much current in the body.

Tesla coils can produce hundreds of thousands of volts at reasonably high currents, but operate well into RF, and are thus a serious burn hazard but leave the heart electrically unaffected.

120V mains will generally not kill you, but has a low enough frequency, high enough voltage, and high enough current that I can if you become entangled with the source and are unable to get free.

I hope this has cleared up some pseudoscience.

Also building your own PSU is not outside the realm of an advanced hobbyist, but you are much better off simply buying them given all the design and build time required. If you want to save some money, look for secondhand PSUs.

Source: electrical engineering student and high voltage enthusiast
16  Bitcoin / Mining / Re: 5830's from Tigerdirect question on: June 11, 2011, 04:07:28 AM
Guess I'll take a code if there are any left.
17  Other / Obsolete (selling) / Re: For sale: unverified paypal account with US $47.65 balance on: June 11, 2011, 03:52:10 AM
All sorts of warning bells start to ring.  Cheesy

I would be more than happy to let someone really trusted around here act as escrow.

Also screw paypal's EULA, haha. In fact, screw paypal. I seriously regret setting up that account instead of receiving giftcards or something instead.
18  Other / CPU/GPU Bitcoin mining hardware / Re: Could someone recommend me a motherboard for 4 cards? on: June 11, 2011, 03:48:45 AM

Question: can either windows or linux support this many GPUs, and does the BIOS?

If the answer is yes, I can 6x 5770 being very practical in this setup.
19  Bitcoin / Mining / Re: Recommendations for utilizing new Mobo on: June 11, 2011, 03:41:52 AM
Theoretically unlimited given the realistic hardware constraints of populating a single motherboard, however I'd like to keep things as economically minded for short-term mining as possible. This is the reason I hopped on the 5830 bandwagon a long time ago, obviously I need some other ideas now.
20  Bitcoin / Mining / Re: If I bought a bunch of 5830's. any interest? on: June 11, 2011, 03:39:42 AM
Also here's a protip: microcenter will do pricematching with newegg without manager approval, and any site with manager approval. Also I've talked to around three different employees at my local microcenter who are all miners using employee discounts to get hardware cheap.

Newegg is currently out of stock of this card, but had it for $160. I plan to head in tomorrow and show them google's cache of newegg's page for this card and see if they'll match.
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