My system is HP Pavilion 690-0034 with Ryzen 7 2700, 16GB RAM, Radeon RX 580 4GB, upgraded Samsung 970 Pro SSD, 1 HDD, and 1 optical drive. The PSU is 400 watts, rated 80 Plus Platinum. I want to upgrade my GPU to GeForce RTX 2070 Mini ITX 8G from Gigabyte, but my PSU is kinda proprietary in...