The graphics driver issue is unfortunately expected with the F43 to F44 upgrade, for that generation of GPU. The black screen was not expected though - in theory it should fall back to nouveau which should work… just slowly. Were you using X11 and not Wayland back on F43?
On your new install, it sounds like you have 2 different issues:
- Slow graphics? Check if your NVIDIA driver is installed by running the
nvidia-smicommand. (I would also suggest switching back to Wayland, as it is better supported these days.) - Heavy HDD activity? Try finding what process is responsible for the heavy disk activity with a tool like
iotopor application like Mission Center.
It would help to have more info about your setup. You can gather the info with fpaste, see this topic: What is fpaste and how can I use it?