1. run DDU in safe mode and clean old Nvidia driver completely (or simply do a fresh Win10 20H2 install)
2. check if GPU has all powercables connected
3. do a CMOS
4. only enable XMP (also give RAM 1.4V) + maybe undervolt your CPU a litte
btw - what MoBo, what CPU, what PSU etc
PC: R7 2700X @PBO + RX 580 4G (1500MHz/2000MHz CL16) + 32G DDR4-3200CL14 + 144hz 1ms FS P + 75hz 1ms FS
Laptop: R5 2500U @30W + RX 560X (1400MHz/1500MHz) + 16G DDR4-2400CL16 + 120Hz 3ms FS