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
ASUS NVIDIA GeForce GTX 1660 Ti Models With 3 GB VRAM Registered With the EEC | TechPowerUp
NVIDIA GeForce GTX 1660 SUPER Specs | TechPowerUp GPU Database