just to add one more experience with vegas if it adds on free wisdom subject

decided to build a 6 vega rig (my first one ever). knew btc from 2013, looked again at 2014-2015 and din't do anything.  i just decided to give it a try just to not regret it again for not doing something, even if i am very late  in this and I know  what i am messing with.
ordered 6 vega 64 (2  liquid from saphire and 4 gigabyte watercooled) late november-early december at amazon at 599 uk Pounds.
the last 2 gigabyte delivered mid and end december. The last 2 are to be return back to Amazon as not working ones. (problematic ones- the one crashes the system as hard as you try and the second is not recognized by windows as a gpu anymore-worked a bit in the beggining and then was lost completely-not recognized as hw anymore. tried also on second motherboard, another rig of a friend with same behaviour.)

So have spent almost a month with setup of the rig with the 4 cards (mobo Asrock btc pro r2.0, 2 *evga 1000 PSU  , win 10 pro etc). Followed steps from various sites (vega.miningguides covers most of it), installed drivers numerous times and windows from scratch 2 times to make it stable-my first ever rig, so newbie completely. had many years to deal with pc equipment). currently run a bat file to disable/enable cards, set settings by overdrivetool and run the miner of  choice.
Have a stable system now , system doesn't need reboot , runs stable for almost a week now  -will let it run to see if it crashes sometime.
(not optimum setup though, 250-255W per card , mem 1100, tp -30% and fan speed at some 2k are all the changes i have done, with overdriventool , no registry files used so far, might try changes when add a  5th nitro saphire i will get the following days)
mainly use xmrstak for etn, sumo, monero with good results. Have also tried nicehash , working  perfect on cryptonight, just can't find a reason to leave the coins to someone else.
pulling some 2010-2040 hash/sec per card  constantly. temps at 45-46 (watman readings, not using this anymore other than that) . Rarely using 2 other utilites ie GPU-z to read gpu settings like temp etc due that it affects hash power everytime i use them, so need to disable/enable the cards again.

due to the failures of the last 2 cards , i don't really want to push the remaining ones hard or to do many changes to the setup.
looking to add 2 more vega (if found anyway- i stopped asking for a replacement from amazon due to last 2 failures-not sure if i should question gigabyte reliability, or vega in general-since the last 2 cards were failures the only thing i can assume is that the cards came from returns from other customers and they were problematic from start-shame that they send them to customers)

initial target of the mining effort was  to see if a system with 6 vegas 64   can give 20 euros per day recurring revenue (on average-low set target and a ROI of some 6-8+ months).  
after less than a month ,monthly target has met . I meet the target with just 4 cards and not 6. With some lack on sumo, have some 0,1 btc (0,75 btc , along with some monero and   etn  )
For as long as it lasts, and if the whole industry doesn't collapse overnight, i am pretty sure that mining can work.
Also as a thought, i am leaning towards the high end (either vega or 1080ti) with a reasoning that even in the worst case scenario of downward trend, if there are any cards left producing even minimal revenue, these will be the top ones currently (ROI will be in red on this scenario but anyway).

Thinking seriously to build a second rig but on 1070 or 1080ti, seem to have better availability and also to diversify the mining  to other coins also.