Most cost effective rig setup?

I'm currently mining out of my desktop PC which… Is what it is. I have a green light from the other half to invest in a rig which I'll be migrating cards to and eventually filling out. I browsed the sub for some hardware info but some of it is a bit dated. I would ideally like to have 6 to 8 cards per rig. And it would have to be able to support 2xxx and 3xxx series cards.

As far as motherboard, CPU, RAM and PSU go; Whats the cheapest combo, ideally without cutting corners on the PSU? Lol.

Thanks in advance!

Edit: Don't need info on GPUs. I've got that covered already.