Apparently you can overclock the GTX 1660 Ti VRAM an extra 1000MHz and it's perfectly stable. I've played FarCry 5, COD BO3, and Minecraft with SEUS PTGI all for a few ours
MSI Nvidia GeForce GTX 1660 Gaming X Review - an Even Lower Cost Turing Option - Page 4 of 11 - Bjorn3D.com