Username: keybaud

Thanks

/edit 3 Sep 11. Added photo link and returned from 4 weeks out of the UK, so updating post.

I'm selling my fully operational mining rig as I am regularly out of the country, so can't leave it running anymore.

GPUs: 3 x XFX Radeon HD5870 1GB (Single resistor dummy plug on cards 2 and 3)
Motherboard: Intel 975XBX
CPU: Intel E6400 & HSF
PSU: Coolermaster Gold Silent 700W (80+ Gold certified)
RAM: 1 GB Crucial DDR2
Hard Drive: Western Digital SATA 250 GB
DVD: Pioneer IDE A105 slot DVD (not connected, but cables present).
Case: Tower case with exhaust fan at front and rear and two inlet fans blowing air directly onto the 3 graphics cards from holes cut in the case side panel. This keeps the cards cooler than having air blow onto the cards with the case removed.

The HD 5870s run at 920/300 to reduce the heat and power consumption slightly, although they can go higher. They produce over 400 GH/s each with Phoenix using the latest phatk kernel on Windows XP with the 11.6 ATI drivers and SDK, for a total of just over 1,200 GH/s.

I will leave the OS on the hard drive, which is a valid Windows XP install, and will also leave all the configurations set up with just the username and passwords blanked. There are three separate installations of Phoenix for each card, so 9 in total. The batch files are setup for BTCguild.com, bitcoins.lc and bitcoinpool.com. The aggression timings have been tuned to maximise the total GH/s for the PC.

£535 collection or £550 inc P&P.

I will accept payment by Paypal, but the price will increase by £10 to partially cover their 3% fee.

PM or post replies here.

You can set an email to be sent out based on the MH/s the pool sees. If you get your efficiency problem, your card may have a high hash rate but the pool will see a low one due to the low number of solved shares.

A standard HDMI port outputs digital in the block connector and standard analogue VGA on the cross connector. All a HDMI to VGA plug does in put the analogue connectors to a VGA pin format.

Analogue VGA outputs a Red, Green and Blue signal, known as RGB. All you need to do is put a resistive shunt across one channel to make Windows think you have a monitor attached.

Putting a resistor across the R, G or B channel (or all 3 if you mistakenly think it will make a difference) has the same affect whether you use the HDMI analogue connectors or the VGA adaptor analogue connectors. If you cross the pins on the HDMI to VGA adaptor it will have EXACTLY THE SAME AFFECT as if you'd crossed them on the HDMI connector.

The only difference using an adaptor has is that it may cost you more money.

Newsflash - the malware exists and has been found by Symantec.

http://www.pcpro.co.uk/news/security/368149/symantec-warns-of-trojan-targeting-bitcoin

http://www.symantec.com/connect/blogs/all-your-bitcoins-are-ours

Malware is being written to steal wallet IDs:

http://www.wired.com/threatlevel/2011/06/bitcoin-malware/

Think of it in simple terms:

Two groups of machines, each looking at the same block of numbers and both groups have the same rate of finding a block. 10 slow machines that each find a block every 10 seconds, so an average of one block a second, and 1 fast machine that finds a block every second.

If the block of numbers are the same, the 10 machines only have a chance to find the tenth block, as the fast machine will have found the first 9 before the 9 slower machines. The fast machine will then start to work on the 10th block at the same time the 10th machine has 1 second left of the 10 seconds to find it.

So, what does this mean?

If you have a slow machine and are solving blocks that faster machines are also solving, then you have a very reduced chance of finding a valid block.

I'm running 3 x HD5870 on Windows XP with an Intel DX975XBX motherboard and an Intel E6400 with 1 GB DDR2. I'm using single resistor dummy plugs in cards 2 and 3 and all 3 cards are running at 950/300. I run 2 Phoenix instances on each GPU with identical settings, so I cover 2 pools in case one has problems. My total hash rate is just over 1,200 MH/s.

Not an XP/Windows problem, but to get around the heat issue, as the cards are so close together, I use insulating spacers to push the cards apart and I've cut holes in the case and fitted 2 fans that blow air directly onto the middle card.

The pool hash rate is an estimate, whereas the client hash rate is your GPU's hash rate.

Do you actually mean a different measure and not hash rate?

I run 2 Phoenix clients per GPU (I have 3 x HD5870) and I run them both at the same Aggression. This splits the work between them evenly until one of the pools has a hiccup. My total hash rate is slightly higher than running one instance of Phoenix per GPU.

Why would you get more stale shares using more than one miner per GPU?

The hash rate at the pool is an estimate, so nowhere near as accurate as the client reported hash rate.

680W 1,250 MH/s (3 x HD5870)

The HDD I'm currently using draws too much power for what it's used for and I've not reduced the voltage on the cards, so the power could be lower if I had the enthusiasm to reduce it.

Legally the bitcoins you mine belong to then company that owns the hardware and pays the electric bills, so your actions are no different to stealing cash or equipment from them. I'm not saying don't do it, I'm just saying that I hope this job and your career in IT is worth a lot less than the bitcoins you'll get.

Nothing to do with ATI or NVidia, it's a Windows limitation.

I've done some poking and the problem would appear to be how Windows XP stores the details in the command prompt window. As the miner is creating a new line every few seconds and Windows remembers everything in the command prompt window, the memory required to do this will grow until you eventually get an out of memory error when the virtual memory limit is reached. Because I'd disabled virtual memory, I was reaching the limit much earlier than usual. This will also be why the hard drive was being used far more than I expected it to, as it never went into shutdown when mining with virtual memory enabled.

I don't know if this problem occurs on other versions of Windows, as I'm only using XP.

PHOENIX MEMORY LEAK?

In an effort to reduce the amount of heat my PC generates, I set my copy of Windows XP to not use any Virtual Memory so it wouldn't access the hard drive as much. I have 1 GB of memory fitted to the PC and when I run 6 Phoenix clients I am using 740MB. If I leave the PC for an extended period, over 24 hours, Phoenix will start generating errors and I get an 'Out of Virtual Memory' message from Windows. I'll try and copy the error message next time, but I'd already rebooted the PC when I started to write this.

The implication here is that Phoenix has a memory leak of some kind, as there is no reason the the extra 260 MB of RAM needs to be used.

The price has always gone up before the difficulty, so by the logic you're using the bitcoin difficulty is reacting to the market....

210W seems very low, is this calculated or measured at the wall? PSUs have losses, so a 150 Watt video card would be pulling 180 Watts from the wall with an 80% efficient PSU.

If you're using the PC at the same time, are you sure your getting 94.5 MH/s out of it?

If you're not using the PC, do you usually leave it on 24/7 or are you only mining when you turn the PC on? If it's the latter, then your BTC rates per day will be less, if it's the former, then you were pouring money down the drain before you started mining. If the PC is running other services 24/7 then the costs are already incurred, but do these services affect the hash rate. i.e. what is the true cost of mining vs the true profit.

Difficulty is going up by 30% tomorrow, I believe, so your amount of bitcoins will reduce.

Not trying to be negative, but a lot of people are throwing money away in the false illusion that they are making money through mining.

4870 is 150W at stock, which is why I stopped mining on mine, as I was paying more for electricity than I was getting back from BTC. Not sure if it's profitable now BTC value have gone up, as the difficulty has also gone up.

It is worth noting that lots of miners actually undervolt their GPUs, so they use less power, as opposed to the gaming community who overvolt to get the max speed out of them.

The logic is as follows:

V=IR and P=IV=(I^2)R.
R is constant so I is proportional to V. i.e. I rises by the same percentage as V, when you over or under volt.

Increasing the voltage by 20% may increase your hash rate by 10%, but it will increase your power costs by 44%. (1.2 x 1.2 = 1.44)
Decreasing the voltage by 10% may not affect your hash rate, but will reduce your power costs by 19%. (0.9 x 0.9 = 0.81)

So, the 10% increase in hashing by overvolting costs 72% more in electricity than undervolting for the original hash rate.