Set up a GPU rig 4 years ago. It was super finicky to get it right. Used CGminer back then too. It seemed on my cards if you chose all the variables for the cards instead of letting them default it worked worlds better. My cards ran about 15 degrees colder and faster once I dialed in the settings with 0 hardware errors. It was a lot of fun tuning them. Reminded me of setting different fuel ratios for different RPM on a bike. Lol! Happy mining! I should build another rig.