Under the Photoshop preference in the Performance section, does it see the Nvidia card and is it checked on?
I have seen sometimes where Photoshop reverts to the selected card to the Intel integrated GPU, even though the system has a dedicated card.
If it see the card and it is turned on then try resetting the Photoshop preferences. I have seen corrupted prefs files cause the GPU to not work correct too.
Let me know after doing this and we can proceed if needed.