That is high voltage RAM, and while you can generally run RAM at 1.65V without damaging Sandy Bridge components, that happens to be high voltage RAM that isn't particularly fast. It an older DDR3 product, and at the time it was sold, higher voltage may have been necessary to run DDR4-1600 at tighter timings, as that kit does.
But you absolutely should not buy new DDR3 RAM at this point. It is obsolete, overpriced, and cannot be used on any current system. I really don't think it's the cause of the problem anyway. PCPartPicker just spits out answers based on canned warnings, not based on any particular knowledge of the products.
I do want to let you know that your CPU will bottleneck a GTX 1080 significantly in modern games. I would not make the investment in that GPU unless you were willing to overclock the CPU to at least 4GHz. Another option would be to invest in a new platform, but obviously that will cost a great deal of money.
By the way, the Noctua fans can be raised to clear the tall heatsinks on the RAM. That isn't an issue.