CGminer for scrypt mining tutorial

First off, the original CGminer for GPU is dead. All 3.8 and newer builds are made for ASICs only. Luckily, it has been forked, and scrypt-mining on GPU has been kept. Get kalroth's CGminer fork at http://k-dev.net/cgminer/. Also have a look at this thread at overclock.net.

Configuring CGminer is quite complicated (it is JSON formatted), but my basic one goes like:

{
"pools" : [
{
"quota" : "20;stratum+tcp://server1:3333",
"user" : "x.x",
"pass" : "x"
},
{
"quota" : "50;stratum+tcp://server2:3333",
"user" : "x.x",
"pass" : "x"
},
{
"url" : "stratum+tcp://server3:3333,
"user" : "x.x",
"pass" : "x"
},
{
"quota" : "10;stratum+tcp://server4:3333",
"user" : "x.x",
"pass" : "x"
},
{
"quota" : "20;stratum+tcp://server5:3333",
"user" : "x.x",
"pass" : "x"
}
],
"failover-only" : true,
"load-balance" : true,
"scrypt" : true,
"kernel" : "scrypt",
"intensity" : "15,13",
"thread-concurrency" : "4476,3198",
"gpu-threads" : "1",
"gpu-platform" : "1"
}

This config turns on the normal scrypt module, as you can see.

Also it enables failover and load balancing. As you can see, server 1,2,4,5 shares their quota amd server 3 is only a fail-over, but it will still failover to any alive pool as long as a server with quote demand is dead.

20+50+10+20 = 100 %.

Notice the "quota" parameter replacing the usual "url" parameter, and that is add a comma separator after the quota specified before the url!

Intensity: Is just how much steam the cards can handle. If you see in the CGminer console that you are getting HW errors, lower the intensity. 15 is a bit high, but I get no errors. 13 is more common, but still gives me a HW error of 1 per day or so. That is not good, so I should lower intensity to 12 and see how it goes.

Note the comma-separation on the parameters that supports it. Generally PCIe slot 0 is the first, PCIe slot 2 is the second, etc!

Thread concurrency: Is calculated by taking number of GPU shaders and multiplying by 4 (for the 6xxx and 7xxx series, other models has other optimal calculations.) and remove 4.

GPU Platform: Normally, the platform available on PCIe slot 0 becomes gpu-platform 0. That means if you have an Nvidia card in slot 0 like me, and 2 AMD cards on slot 1 and 2, it becomes platform 1. So platform 1, card 0 and 1 is my active cards in CG miner. cudaminer would then need the opposite config, pretty much.

Starting up CGminer from a batch file:

@echo on
ECHO "cgminer miner startup"
ECHO.
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
cgminer.exe --config=cgminer.conf

setx works on Windows, as some people dispute. Look at the 'succeeded' return-message in the console.

Simple calculation for two popular cloud miners

bit-miner.com and cex.io

bit-miner.com:

ASSET #1

6x180GH/s = 1080 Gh/s
Number of shares = 10000
1080/10000=0.108, this is the Gh/s per share.
0.108x=1 => 1/0.108 = 9.25 shares per Gh/s
Asset #1 has a price of 5-7, depending on the time. That means on average $55.5 per Gh/s

ASSET #12

3000 GH/s
Number of shares = 30000
3000/30000=0.1, this is the Gh/s per share.
0.1x=1 => 1/0.1 = 10 shares per Gh/s
Asset #12 has a price of 1.5-2, depending on the time. That means on average $17.5 per Gh/s. That is a sweet deal now, but remember that it doesn't start until May!

CEX.IO:

BTC 0.35 per GH/s = $28.25 per GH/s

But this is mining at current difficulty! So even if Bit-Miner.com's Gh/s is about $10 more expensive not, you should recover that by mining at current block difficulty.

At the moment, CEX,.io is the best place for GH/s trading right now.

Here is some referall links for me, if you sign up with my reference, I get a transaction percentage bonus.

If you feel this article helped you, please consider signing up at cex.io

Here you also co-mine IXC, NMC and DVC.

Reserving the right to miscalculations.

ICX and DVC coins can be traded at Vircurex and Cryptsy.
NMC can buy GH/s at CEX.io