Soldato
you would have to be very unlucky to get 2 bad vega 64's that had run fine for months. I have had a bad HDMI cable before which gave me all kinds of trouble and had me looking at other things until I just changed it for the sake of it, and it cured it.
I have to say all though I would say 750w PSU is enough it does not mean it cant fail or have a cap leak. there have been faulty PSU's from good brands reported before, when you have a fault like this it can be a money pit, but also annoying it keep happening.
first thing I would do is swap out PSU and eliminate that first. make sure its a single rail PSU and high enough output. if you have a friend close who would be willing to try one of your cards for a while with a decent system it might save you expense. or even willing to swap out PSU's
Thank you for your quick reply Matt ! Much appreciated.
Well, I have a SuperFlower Leadex GOLD 850W Fully Modular "80 Plus Gold" that was bought from OcUK in end of Nov 2014, so a bit old but should be ok to try with that you think ? Not sure how to find out if it is a single rail PSU though, but I am guessing 850W is high enough output, or you referring to something else ?