You can get Vega 64 GPU but no good quality PSU?? anyway, check out this list for PSU http://www.tomshardware.co.uk/forum/id-2547993/psu-tier-list.html , but I wouldn't recommend to put a high end GPU on a bronze efficiency PSU... the cpu doesn't matter for Vegas, you can choose the cheapest you can get, and 8GB RAM is more than enough for GPU mining...btw, that motherboard is DDR3 SDRAM compatible, DDR4 won't fit into it... also I recommend this site for your Vega 64 rig setup https://vegamining.blogspot.com