Need to get some bases covered first to make sure your base is solid to trouble shoot from
Is the firmware on your SSD's up to date?
Is your motherboard's BIOS up to date?
Is your Windows install up to date?
Do you have the latest AM4 chipset drivers installed from AMD.com?
Did you run the program called "DDU" to remove all past present GPU drivers of whatever video cards you have ran on this install of Windows prior to installing your 7900XTX?
What power supply make/model/age are you running?
Are you running separate power cables from your PSU to each power input on your GPU?
Have you checked your CPU/GPU temps while your system is under load? If so, what are they?
What speed is your RAM actually running at?