I chose my GPUs poorly. Went with 1050 GTX because the Radeons were sold out and the 1060/1070s were significantly more expensive and tougher to obtain, but they are far more efficient. I suggest you get the 1070s.
I'm not sure why it's so difficult. But I'll give you a quick rundown of what I went through yesterday:
-finally got 3 cards working, left it that way for ~24 hours
-decided to try to push it to 4 cards
-OS wouldn't boot up, hell monitor wouldn't even boot up.
-removed 4th card and tried to go back to 3 cards
-I couldn't even get 2 cards working! Was stuck on 1 card and spent hours tinkering to get back to 2, now finally got back to 3.
I have a feeling it's a combination of my GPUs/motherboard/power supply and 4-6 cards should be possible, but regardless, I don't think you should build a mining rig right now. Ethereum is about to perform a hard fork where they'll reduce mining rewards from 5 to 3 ETH, other coins are less profitable to mine, and it takes a long time to recoup investment under even the most optimistic conditions. That said, if you avoided my mistakes and did everything absolutely perfectly and had no issues, I could see it possible to make maybe $3 a day on a rig that might cost you ~$2500. I'll probably write a blog on troubleshooting issues and what I should have done instead in the next few days.
Thanks for the upvote and insight. $3 a day for a $2500 rig seems really bad ROI. I wonder why it is a boom for so many because the GPUs are still selling like crazy. What about mining ETC just so that you can exchange it for $ or ETH. I am thinking of doing that but don't have anything to test it out. Whattomine.com has them neck and neck but ETC will not increase in difficulty as much as ETH and when people don't see enough earning they will likely go ETC or cryptonight coins.
Anyways I am not a computer expert nor programmer but love crypto. I may have to wait until the ETH hardfork occurs and see how it affects the GPU market. I doubt it will go down if at all, people will just find other coins to mine.
Yea it's tough, probably not worth it. Basically, right now I get about 37.1 MH/s (with 3 GPU running) and make roughly $0.055 in revenue per hour, and if I give every benefit of the doubt, maybe someone can get 6 1070 GTX GPUs working at ~33 MH/s each for 200 MH/s on a 1250 power supply. So let's say someone can make $0.30 an hour before electricity as a max. Let's conservatively assume they pay $0.10 an hour in electricity, which equates to $0.20 * 24 = $4.80 a day, or break even in 1.5 years. Rough gig, but have to remember that the hardware has value and can be sold or run for a long time and if other coins become more profitable you can switch to those.
Just seems like a very long time to get to break even, and it's better to take your fiat and buy crypto directly than to mine unless you have either solar power or very cheap electricity -- Iceland or China.
I'd guess it's still popular because there are people like me who try it for fun, or people who overestimate how much they can make.
I want to build one for fun too but main reason is for profit. The more profit the more fun. That is just simple math here. Yet actually doing it is the hard part. Each passing day I do not go out and take a leap I will only feel I am missing out and the higher the difficulty.
37.1MH/s on 3x1050s actually sounds decent. I am likely going to pay more for new cards because I just don't trust the run time on the used cards. I have read many bad stories like the miners that were built and resold burn out in a few months because they were running of fumes. Resale values of those are likely dropping or will drop due to usage. I have been on ebay for two weeks and the rig prices are still ridiculous. Going to wait even though difficulty is on the rise.