From what I understand in your post, you have a 2 GPU's, and you consider that one of those is faulty.
let me clear first, why did you replace your PSU in the first place when it is mining without problems?
I was reusing some hardware from a old PC, and was using a PSU I bought back in 2009 and I was afraid because it's old so went swap it with my PC's Seasonic one.
Are your GPU's identical?
Both are GTX 1060 but from different brands.