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Bitcoin Currency and GPU Mining Performance Comparison

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What is a Bitcoin?

This article looking at Bitcoins and the performance of various GPUs with mining them was really a big team effort at PC Perspective.  Props goes out to Tim Verry for doing the research on the process of mining and helping to explain what Bitcoins are all about.  Ken Addison did a great job doing through an alottment of graphics cards running our GUIMiner and getting the data you will see presented later.  Scott Michaud helped with some graphics and imagery and I'm the monkey that just puts it all together at the end.

** Update 7/13/11 **  We recently wrote another piece on the cost of the power to run our Bitcoin mining operations used in this performance article.  Based on the individual prices of electric in all 50 states of the US, we found that the cost of the power to run some cards exceeded the value of the Bitcoin currency based on today's exchange rates.  I would highly recommend you check out that story as well after giving this performance-based article a thorough reading.  ** End Update **

A new virtual currency called Bitcoin has been receiving a great deal of news fanfare, criticism and user adoption. The so called cryptographic currency uses strong encryption methods to eliminate the need for trust when buying and selling goods over the Internet in addition to a peer-to-peer distributed timestamp server that maintains a public record of every transaction to prevent double spending of the electronic currency. The aspect of Bitcoin that has caused the most criticism and recent large rise in growth lies in is its inherent ability to anonymize the real life identities of users (though the transactions themselves are public) and the ability to make money by supporting the Bitcoin network in verifying pending transactions through a process called “mining” respectively. Privacy, security, cutting out the middle man and making it easy for users to do small casual transactions without fees as well as the ability to be rewarded for helping to secure the network by mining are all selling points (pun intended) of the currency.

When dealing with a more traditional and physical local currency, there is a need to for both parties to trust the currency but not much need to trust each other as handing over cash is fairly straightforward. One does not need to trust the other person as much as if it were a check which could bounce. Once it has changed hands, the buyer can not go and spend that money elsewhere as it is physically gone. Transactions over the Internet; however, greatly reduce the convenience of that local currency, and due to the series of tubes’ inability to carry cash through the pipes, services like Paypal as well as credit cards and checks are likely to be used in its place. While these replacements are convenient, they also are much riskier than cash as fraudulent charge-backs and disputes are likely to occur, leaving the seller in a bad position. Due to this risk, sellers have to factor a certain percentage of expected fraud into their prices in addition to collecting as much personally identifiable information as possible. Bitcoin seeks to remedy these risks by bringing the convenience of a local currency to the virtual plane with irreversible transactions, a public record of all transactions, and the ability to trust strong cryptography instead of the need for trusting people.

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There are a number of security measures inherent in the Bitcoin protocol that assist with these security goals. Foremost, bitcoin uses strong public and private key cryptography to secure coins to a user. Money is handled by a bitcoin wallet, which is a program such as the official bitcoin client that creates public/private key pairs that allow you to send and receive money. You are further able to generate new receiving addresses whenever you want within the client. The wallet.dat file is the record of all your key pairs and thus your bitcoins and contains 100 address/key pairs (though you are able to generate new ones beyond that). Then, to send money one only needs to sign the bitcoin with their private key and send it to the recipient’s public key. This creates a chain of transactions that are secured by these public and private key pairs from person to person. Unfortunately this cryptography alone is not able to prevent double spending, meaning that Person A could sign the bitcoin with his private key to Person B, but also could do the same to Person C and so on. This issue is where the peer-to-peer and distributed computing aspect of the bitcoin protocol come into play. By using a peer-to-peer distributed timestamp server, the bitcoin protocol creates a public record of every transaction that prevents double spending of bitcoins. Once the bitcoin has been signed to a public key (receiving address) with the user’s private key, and the network confirms this transaction the bitcoins can no longer be spent by Person A as the network has confirmed that the coin belongs to Person B now, and they are the only ones that can spend it using their private key.

Keep reading our article that details the theories behind Bitcoins as well as the performance of modern GPUs in mining them!  

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The privacy and anonymity afforded by the bitcoin protocol has received flak recently due to the currency being used to purchase illegal drugs and other products online. The US government has seen a number of members speak out against the currency because of the illegal drug involvement and taxation implications. However, bitcoin is not the only currency that is used by a number of people for illegal uses, and it is certainly not representative of a majority of illegal usage. Regardless of the relatively small number of illegal uses, the privacy afforded by bitcoin is not inherently a bad thing. As the Internet equivalent to a local currency such as cash, bitcoin is able to facilitate a much higher level of anonymity than other currencies used online. The privacy implications are not only good for those mis-using it for nefarious purposes; it is actually a good thing for legal transactions because sellers do not need to collect nearly as much personally identifiable information in order to trust the buyer enough to go through with the sale. Traditionally, telephone numbers, addresses, financial information, and other personal information has been required in order for even the most mundane transactions over the Internet as sellers needed to protect themselves as much as possible from fraud.

July 12, 2011 | 08:26 PM - Posted by Adster (not verified)

Any reason the AMD 6950 & 6970 cards was left out of the experiment? As the flagship AMD single GPU cards, I think this data would be really salient. Is there another card on the list from which we could easily extrapolate 6950/6970 performance?

July 12, 2011 | 10:06 PM - Posted by Tim Verry

In my personal testing, the 6950 gets somewhere around 340 mhash/s with a few optimizations. Overclocking and unlocking can get you around 400. You can get the 6950/70 performance by dividing the results of the 6990 GPU results in the graph.

My understanding of the GPUs used were based on what was available in house for testing.

July 12, 2011 | 10:12 PM - Posted by Tim Verry

More specific results (please keep in mind that I am using different settings than Ken so they are not necessarily comparable):

My 6950 unlocked to 6970 shaders at 840 core gets 372.7 mhash/s using GUIMiner, and two kernel tweaks of the poclbm kernel, and AMD Cat 1.7 drivers and whatever version of Stream SDK comes with that. I'm further using the following flags which are gfx card version specific: -k poclbm VECTORS BFI_INT AGGRESSION=9 WORKSIZE=128

Hope it helps :) If you have any questions please feel free to ask.

July 13, 2011 | 07:22 AM - Posted by Adster (not verified)

Hi Tim,

I'd be interested in a little more information. I'm running a Sapphire 6950 2GB with unlocked (6970) shaders (but not flashed to 6970 speeds; I just OC when I need the boost). I'm also sporting a Core2Duo E8400 OC'd to 3.6 Ghz. I started mining last night, following the guides Ryan mentioned, and I'm consistently getting 320 Mhash/s, not the 340 you mentioned was possible with a few "optimizations."

Do you know if the optimizations you mentioned (the flags) should work for my 6950; you said they are gfx card version specific - did you mean vendor specific, or just 6950 specific? Is it possible to use those flags when I'm using the GUIMiner, or do I need to be using a console? Thanks for any input!

July 13, 2011 | 01:22 PM - Posted by Tim Verry

Hi Adster, I am running a XFX 6950 2GB card with an edited BIOS to have unlocked shaders but not 6970 speeds (though the card is capable of running at them, I didn't want to risk running the memory at the higher speed full time).

The flags that I mentioned will work for you 6950, they are specific to the version of card you have, in this case these flags are best used with AMD 6xxx series cards. You can set the flags in the GUIMiner extra flags area; however, you will need to edit the poclbm kernel file for the other optimizations. You can find those by searching the bitcoin forums for kernel optimizations.

I hope it helps, let me know if you need any help in sqeezing all the mhash possible outta that card :)

April 20, 2013 | 04:47 PM - Posted by Anonymous (not verified)

I have Gigabyte 6950 and overclocked at 900mhz it has 370MH/s , sometimes goes over, but constantly is 370MH/s, it is good for cost effective?

July 21, 2011 | 07:20 AM - Posted by Ukprotect (not verified)

My HD 6950 achieves 362 Mhash/s, I use the following config:
The HD6950 is flashed with 6970 bios, GUIMiner, flags: -v -w128 -f1, Core Clock=890, Memory Clock=1580, PCI-E x16.

August 25, 2011 | 08:44 AM - Posted by Doc (not verified)

I am running an Asus 6950 with the shaders unlock but not the 6970 bios. I am achieving 379 Mhash/s.

I am running phoenix miner 1.6.2 from a command line (guiminer's front end eats Mhash/s). My switches are -k phatk2 VECTORS BFI_INT AGGRESSION=13 worksize=128 FASTLOOP=false

Also I am running it OCed to 840MHz and the memory underclocked to 750MHz. It seems odd, but underclocking the memory adds another 1-2 Mhash/s.

July 13, 2011 | 08:27 AM - Posted by Ryan Shrout

Honestly, we just didn't test it because we skipped some cards. Looking back, we should have done one of them. You can see on our screenshot of "The Beast" that we eventually plugged one in and got about ~ 344 Mhash/s.

July 16, 2011 | 07:16 AM - Posted by Touche (not verified)

Try here for a lits of cards and their Bitcoin potential : https://en.bitcoin.it/wiki/Mining_hardware_comparison

July 12, 2011 | 09:08 PM - Posted by undersea

OK, who is doing this?

July 12, 2011 | 10:07 PM - Posted by Tim Verry

who is doing what? mining?

July 14, 2011 | 09:01 AM - Posted by Anonymous (not verified)

The Chilean miners, they are doing this for sure...

July 12, 2011 | 11:12 PM - Posted by Anonymous (not verified)

don't count on unlocking a 6950 to a 6970 unless you get n older one. ATI/AMD is crippling the new ones.

July 13, 2011 | 08:42 AM - Posted by neliz (not verified)

No they're not, whoever gave you that idea? NV?

July 13, 2011 | 10:01 AM - Posted by Adster (not verified)

This is a great article, and pushed me over the edge to start mining. The only big question I have (aside from my earlier question about 6950/6970 performance), is how the cost of electricity factors in.

Obviously we are all subject to different utility rates, so you couldn't give a cost-breakdown that would apply to everyone. However, I am curious how much the average cost of electricity would deduct from the profits in your chart?

July 13, 2011 | 03:30 PM - Posted by Tim Verry

Hi Adster, stay tuned to PC Per for that info ;)

July 13, 2011 | 07:09 PM - Posted by Bolas (not verified)

Is it possible to mine bitcoins in using Windows7 64-bit, or do I have to install Linux?

Does the amount of system memory matter when mining bitcoins, or is the graphics card the only real limiting factor?

July 13, 2011 | 10:43 PM - Posted by Anonymous (not verified)

I have a dedicated mining machine which runs 24/7 in the closet (no, really -- it sits in the closet). It has the cheapest AMD CPU I could find (sempron processor), 1GB of ram, a flash drive used as the hard drive running Ubuntu 10.4 on a headless (monitorless) system. The only thing really going on is the 2x5850 Xtreme graphics cards pumping out ~ 700 MHash. When I bought this rig, it ran me $530 after rebates from Tiger Direct.

July 13, 2011 | 10:45 PM - Posted by Anonymous (not verified)

Linux or Windows doesn't matter. Windows will require a dummy plug on any secondary video cards because the OS won't see it unless it has a monitor plugged in.

July 13, 2011 | 07:18 PM - Posted by Allan (not verified)

I did an analysis of the energy costs, which really should be factored in: http://hardware.slashdot.org/comments.pl?sid=2321814&cid=36755990

July 13, 2011 | 08:35 PM - Posted by Ryan Shrout

We did that today as well!

http://www.pcper.com/reviews/Graphics-Cards/Bitcoin-Mining-Update-Power-...

July 13, 2011 | 07:27 PM - Posted by Anonymous (not verified)

The 5770 is also a pretty glaring lack, because it is the one that would compete the most with the 5830. It is definitely not as good, but it is definitely far easier to obtain a 5770 then a 5830.

July 13, 2011 | 08:36 PM - Posted by Ryan Shrout

Good point - we should try to add it this week.

July 13, 2011 | 10:47 PM - Posted by Anonymous (not verified)

5830s are not really hard to find in stock. I get 219 MHash from my 2x5770s -- Pretty far below (80ish?) what a 5830 gets you and they're not that much cheaper.

July 13, 2011 | 08:27 PM - Posted by Anonymous (not verified)

The way bitcoin distribute it fortune is a waste of our limited energy. Please stop it.

This is also not justly correct that only a few people get access to it and most people of the world is not having a chance

July 13, 2011 | 08:36 PM - Posted by Ryan Shrout

Obviously the hope is they spend it and put it back into circulation, right?

July 13, 2011 | 08:46 PM - Posted by Anonymous (not verified)

There is roughly about 8 megawatts being consumed. A diesel train engine generates 4 so the entire network consumes about the same as a train being pulled by two engines.

Whoop de do.

July 13, 2011 | 08:48 PM - Posted by Anonymous (not verified)

You can find complete mining and overclocking guides @ bitclockers.com

My GTX480 makes me 80 dollars a month right now.

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