Hey man,
I just built an nvidia rig. All 1060s. And one of them died within seconds. So I have a 1070 in its place. The rig runs fine with no issues. Ive also done a really mixed card rig on AMD before with a 290x, a few RX 4/500's, and a Vega 64. That rig had some stability issues. But the mixed card rig on nvidia that I just built hasnt had a problem at all.
Any idea of where youre going to buy the cards?
-DMS