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The Von Matrices Could you give a link to a tutorial or a doc that will show you how to setup mine scrypting?
I've had a few people ask me about this, and I've answered this in private messages, but it makes sense to post it here so that I can help more people at the same time. I probably will update this post a few times to clear up any missing or outdated information (last updated 16 December 2013 10:42PM EST).
Feel free to as me any questions about items I may have missed in this post and if it is widely applicable I will add it to this post.
Getting started with scrypt:
There are two options in mining - to mine the coins you want directly, and to mine alternative coins and allow the pool to exchange them for the coins you want. I choose the latter option since I believe in Bitcoin over the other currencies, but it's a decision completely up to you. Of course, you first need to decide what coin you want to hold, and then create a wallet in that coin.
Whatever you choose, I highly recommend using a mining pool, since that will guarantee steady payouts (at the cost of a few percent of payouts) instead of trying your luck at finding a block by doing solo mining. Remember, if you solo mine, you only make money if you find a block; otherwise, you make nothing. With a pool, you earn a share of any blocks found by anyone in the pool proportional to the amount of hashing power you put into the pool.
As far as what pool to use, I don't have any definitive recommendations. I just want to convert to Bitcoin, so the pool I use is
middlecoin.com. It mines all sorts of scrypt coins and changes coin depending on what is most profitable at the moment. You get paid in Bitcoin every 24 hours. If you want to be paid in the native currency like Litecoin or Novacoin, for example, you need to find a pool that mines and pays out in that currency.
When looking for a pool, you of course should consider the fees involved, but it's also worth considering the amount of time the pool is down. Many of the cheaper pools have lower connection reliability, and you may lose more money by not mining when the connection is down than you would be charged in fees. It's hard to evaluate this reliability just by looking at websites, but generally the largest pools got their position because they are the most reliable.
Setting up scrypt mining:
I'm using CGMiner and Windows. There of course are other programs and you can use Linux, but I do not have experience with them. You need CGMiner version 0.7.2 and not the latest version (the later versions have deprecated scrypt mining). You can get it from
http://ck.kolivas.org/apps/cgminer/3.7/cgminer-3.7.2-windows.zip.
The one thing that you must know is that by default Windows limits any program to 512MB of VRAM, and that restriction absolutely kills scrypt mining performance. To remove that limit and allow the program to use up to 100% of available VRAM, you need to create a short batch file that lifts the limit then runs the miner. You just need to create a text document with three lines:
Code:
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
C:\Mining\cgminer-3.7.2-windows\cgminer.exe (or whatever your cgminer directory is)
Then save the text document as a .bat file and open that to run cgminer instead of just clicking on cgminer.exe.
The default parameters of the program are OK to start off with, but you will want to tune them as described later. When you open the program for the first time, it will ask you for the pool link, the miner username, and the miner password. Note that these are not the same as your website, username, and password to the pool you chose. These mining credentials are provided at the pool's website. They don't need to be secure when you create them (since who cares if someone else mines for your account?).
One the program is started, you should save a configuration file so you don't need to re enter these settings every time you start cgminer. Type "s" to get to settings, then "w" to write config file. Just press "enter" to save the default filename. This will create a "cgminer.conf" file in your cgminer directory. This file can be opened in any text editor
Tweaking your settings to get the best hash rate:
I highly suggest reading the SCRYPT-README.txt file in the cgminer directory and that will tell you almost everything you need to know about adjusting settings of the program.
Scrypt mining requires a lot more tweaking than SHA-256 (Bitcoin algorithm) mining. You will need to modify the cgminer.conf file you created earlier. The three important points from the SCRYPT-README file:
--intensity XX (-I XX)
Just like in bitcoin mining, scrypt mining takes an intensity, however the
scale goes from 0 to 20 to mimic the "Aggression" used in mtrlt's reaper. The
reason this is crucial is that too high an intensity can actually be
disastrous with scrypt because it CAN run out of ram. High intensities
start writing over the same ram and it is highly dependent on the GPU, but they
can start actually DECREASING your hashrate, or even worse, start producing
garbage with HW errors skyrocketing. Note that if you do NOT specify an
intensity, cgminer uses dynamic mode which is designed to minimise the harm
to a running desktop and performance WILL be poor. The lower limit to intensity
with scrypt is usually 8 and cgminer will prevent it going too low.
SUMMARY: Setting this for reasonable hashrates is mandatory.
I find that difficulty of 13 is the highest hash rate on most cards. However, you might need to lower this intensity or your air cooled card can overheat. If you experience overheating, it's generally better to lower clock speeds on your card (even below stock speeds) before lowering intensity.
--thread-concurrency:
This tunes the optimal size of work that scrypt can do. It is internally tuned
by cgminer to be the highest reasonable multiple of shaders that it can
allocate on your GPU. Ideally it should be a multiple of your shader count.
vliw5 architecture (R5XXX) would be best at 5x shaders, while VLIW4 (R6xxx and
R7xxx) are best at 4x. Setting thread concurrency overrides anything you put
into --shaders and is ultimately a BETTER way to tune performance.
SUMMARY: Spend lots of time finding the highest value that your device likes
and increases hashrate.
This is important. You should make thread concurrency a multiple of the number of shaders on your card. The advice here is generally good - at about 4x the number of shaders on VLIW4/GCN GPUs, the gains from increasing thread concurrency will level off. you can go higher to get a slightly faster hash rate, but remember that increasing this multiple uses more and more VRAM. When tweaking this you should use a program like GPU-Z and monitor VRAM use so that it is not larger than the amount of VRAM on the card; otherwise, you will lose a ton of performance due to using system memory.
Overclocking your GPU:
Again, the SCRYPT-README file provides some good guidance:
Overclocking for scrypt mining:
First of all, do not underclock your memory initially. Scrypt mining requires
memory speed and on most, but not all, GPUs, lowering memory speed lowers
mining performance.
Second, absolute engine clock speeds do NOT correlate with hashrate. The ratio
of engine clock speed to memory matters, so if you set your memory to the
default value, and then start overclocking as you are running it, you should
find a sweet spot where the hashrate peaks and then it might actually drop if
you increase the engine clock speed further.
Third, the combination of motherboard, CPU and system ram ALSO makes a
difference, so values that work for a GPU on one system may not work for the
same GPU on a different system. A decent amount of system ram is actually
required for scrypt mining, and 4GB is suggested.
Almost everything in the system affects hash rate, so you should not expect to get the exact same hash rate as anyone else using the same card. The rule of thumb is to overclock GPU memory as much as you possibly can, then raise the core speed gradually until the performance begins to drop. You don't really need to push the core to get high hash rates. For my 7970s, 1850MHz memory works best with only a 1050MHz core. As I said earlier, you optimal clock speeds will certainly differ from mine. Also, keep an eye on the number of hardware errors in cgminer, which are listed under "HW:". If everything is working properly, you should get zero hardware errors.
Other things to consider:
If you want your computer to mine continuously, it might be worth using a program like cgwatcher. This program monitors cgminer and your computer's performance and makes changes to ensure that the computer is operational including restarting cgminer or the computer.
http://manotechnology.blogspot.com/p/cgwatcher.html[/QUOTE]