Solid band on zoom in photoshop

Please try to disable the option to "Use Graphics Procesor" from Photoshop by going to Preferences, then Performance. Once done, quit & relaunch Photoshop to check if that helps. 

If it helps, you can check out the steps suggested here:  https://helpx.adobe.com/photoshop/kb/troubleshoot-gpu-graphics-card.html 

If the issue persists, you can try to reset the preferences of Photoshop using the steps described here: 

Preferences in Photoshop (adobe.com) 

Please backup your settings before resetting the preferences. You can check: 

Migrate presets, actions, and settings (adobe.com) 

Another try is to enable the Older GPU Mode option in "Preferences" > "Technology Previews" > "Use Older GPU Mode (pre 2016)". Then goto "Preferences" > "Technology Previews" and enable "Disable Native Canvas". Restart Photoshop. 

If this all doesn't help, we need more informations aubout your system. Maybe you can post your Photoshop system info. In Photoshop goto Help > System Info and hit the copy button. Then paste the entire informations into this thread.