sgminer/doc/FAQ

FAQ

Q: Can I mine on servers from different networks (eg smartcoin and bitcoin) at
the same time?
A: No, cgminer keeps a database of the block it's working on to ensure it does
not work on stale blocks, and having different blocks from two networks would
make it invalidate the work from each other.

Q: Can I configure cgminer to mine with different login credentials or pools
for each separate device?
A: No.

Q: Can I put multiple pools in the config file?
A: Yes, check the example.conf file. Alternatively, set up everything either on
the command line or via the menu after startup and choose settings->write
config file and the file will be loaded one each startup.

Q: The build fails with gcc is unable to build a binary.
A: Remove the "-march=native" component of your CFLAGS as your version of gcc
does not support it.

Q: Can you implement feature X?
A: I can, but time is limited, and people who donate are more likely to get
their feature requests implemented.

Q: Work keeps going to my backup pool even though my primary pool hasn't
failed?
A: Cgminer checks for conditions where the primary pool is lagging and will
pass some work to the backup servers under those conditions. The reason for
doing this is to try its absolute best to keep the GPUs working on something
useful and not risk idle periods. You can disable this behaviour with the
option --failover-only.

Q: Is this a virus?
A: Cgminer is being packaged with other trojan scripts and some antivirus
software is falsely accusing cgminer.exe as being the actual virus, rather
than whatever it is being packaged with. If you installed cgminer yourself,
then you do not have a virus on your computer. Complain to your antivirus
software company. They seem to be flagging even source code now from cgminer
as viruses, even though text source files can't do anything by themself.

Q: Can you modify the display to include more of one thing in the output and
less of another, or can you change the quiet mode or can you add yet another
output mode?
A: Everyone will always have their own view of what's important to monitor.
The defaults are very sane and I have very little interest in changing this
any further.

Q: What are the best parameters to pass for X pool/hardware/device.
A: Virtually always, the DEFAULT parameters give the best results. Most user
defined settings lead to worse performance. The ONLY thing most users should
need to set is the Intensity for GPUs.

Q: What happened to CPU mining?
A: Being increasingly irrelevant for most users, and a maintenance issue, it is
no longer under active development and will not be supported. No binary builds
supporting CPU mining will be released. Virtually all remaining users of CPU
mining are as back ends for illegal botnets. The main reason cgminer is being
inappopriately tagged as a virus by antivirus software is due to the trojans
packaging a CPU mining capable version of it. There is no longer ANY CPU mining
code in cgminer. If you are mining bitcoin with CPU today, you are spending
1000x more in electricity costs than you are earning in bitcoin.

Q: GUI version?
A: No. The RPC interface makes it possible for someone else to write one
though.

Q: I'm having an issue. What debugging information should I provide?
A: Start cgminer with your regular commands and add -D -T --verbose and provide
the full startup output and a summary of your hardware, operating system, ATI
driver version and ATI stream version.

Q: Why don't you provide win64 builds?
A: Win32 builds work everywhere and there is precisely zero advantage to a
64 bit build on windows.

Q: Is it faster to mine on windows or linux?
A: It makes no difference. It comes down to choice of operating system for
their various features. Linux offers much better long term stability and
remote monitoring and security, while windows offers you overclocking tools
that can achieve much more than cgminer can do on linux.

Q: Can I mine with cgminer on a MAC?
A: cgminer will compile on OSX, but the performance of GPU mining is
compromised due to the opencl implementation on OSX, there is no temperature
or fanspeed monitoring, and the cooling design of most MACs, despite having
powerful GPUs, will usually not cope with constant usage leading to a high
risk of thermal damage. It is highly recommended not to mine on a MAC unless
it is to a USB device.

Q: I'm trying to mine litecoin but cgminer shows MH values instead of kH and
submits no shares?
A: Add the --scrypt parameter.

Q: I switch users on windows and my mining stops working?
A: That's correct, it does. It's a permissions issue that there is no known
fix for due to monitoring of GPU fanspeeds and temperatures. If you disable
the monitoring with --no-adl it should switch okay.

Q: My network gets slower and slower and then dies for a minute?
A; Try the --net-delay option.

Q: How do I tune for p2pool?
A: p2pool has very rapid expiration of work and new blocks, it is suggested you
decrease intensity by 1 from your optimal value, and decrease GPU threads to 1
with -g 1. It is also recommended to use --failover-only since the work is
effectively like a different block chain. If mining with a minirig, it is worth
adding the --bfl-range option.

Q: Are OpenCL kernels from other mining software useable in cgminer?
A: No, the APIs are slightly different between the different software and they
will not work.

Q: I run PHP on windows to access the API with the example miner.php. Why does
it fail when php is installed properly but I only get errors about Sockets not
working in the logs?
A: http://us.php.net/manual/en/sockets.installation.php

Q: What is a PGA?
A: At the moment, cgminer supports 3 FPGAs: BitForce, Icarus and ModMiner.
They are Field-Programmable Gate Arrays that have been programmed to do Bitcoin
mining. Since the acronym needs to be only 3 characters, the "Field-" part has
been skipped.

Q: What is an ASIC?
A: Cgminer currently supports 2 ASICs: Avalon and BitForce SC devices. They
are Application Specify Integrated Circuit devices and provide the highest
performance per unit power due to being dedicated to only one purpose.

Q: Can I mine scrypt with FPGAs or ASICs?
A: No.

Q: What is stratum and how do I use it?
A: Stratum is a protocol designed for pooled mining in such a way as to
minimise the amount of network communications, yet scale to hardware of any
speed. With versions of cgminer 2.8.0+, if a pool has stratum support, cgminer
will automatically detect it and switch to the support as advertised if it can.
If you input the stratum port directly into your configuration, or use the
special prefix "stratum+tcp://" instead of "http://", cgminer will ONLY try to
use stratum protocol mining. The advantages of stratum to the miner are no
delays in getting more work for the miner, less rejects across block changes,
and far less network communications for the same amount of mining hashrate. If
you do NOT wish cgminer to automatically switch to stratum protocol even if it
is detected, add the --fix-protocol option.

Q: Why don't the statistics add up: Accepted, Rejected, Stale, Hardware Errors,
Diff1 Work, etc. when mining greater than 1 difficulty shares?
A: As an example, if you look at 'Difficulty Accepted' in the RPC API, the number
of difficulty shares accepted does not usually exactly equal the amount of work
done to find them. If you are mining at 8 difficulty, then you would expect on
average to find one 8 difficulty share, per 8 single difficulty shares found.
However, the number is actually random and converges over time, it is an average,
not an exact value, thus you may find more or less than the expected average.

Q: Why do the scrypt diffs not match with the current difficulty target?
A: The current scrypt block difficulty is expressed in terms of how many
multiples of the BTC difficulty it currently is (eg 28) whereas the shares of
"difficulty 1" are actually 65536 times smaller than the BTC ones. The diff
expressed by cgminer is as multiples of difficulty 1 shares.

Q: Can I make a donation in litecoin?
A: Yes, see SCRYPT-README for the address, but the author prefers bitcoin if
possible.

Q: My keyboard input momentarily pauses or repeats keys every so often on
windows while mining?
A: The USB implementation on windows can be very flaky on some hardware and
every time cgminer looks for new hardware to hotplug it it can cause these
sorts of problems. You can disable hotplug with:
--hotplug 0

Q: What should my Work Utility (WU) be?
A: Work utility is the product of hashrate * luck and only stabilises over a
very long period of time. Assuming all your work is valid work, bitcoin mining
should produce a work utility of approximately 1 per 71.6MH. This means at
5GH you should have a WU of 5000 / 71.6 or ~ 69. You cannot make your machine
do "better WU" than this - it is luck related. However you can make it much
worse if your machine produces a lot of hardware errors producing invalid work.