enable hardware acceleration on GTX 1660 or offer another hardware acceleration system than CUDA that doesn't support all graphics cards
Kyle Plumadore (Adobe) commented
The GTX 1660 should be supported. If you have CUDA selected in the project renderer dropdown, Premiere will use your GPU to accelerate effect rendering where possible. Keep in mind, not all effects have GPU acceleration, and it's possible that you may experience low GPU utilization if you have a performance bottleneck elsewhere - e.g. encoding/decoding.