Dell Inspiron N5720 after installing display/video drivers the screen or display is flickering. What is the main problem on this issue?

the display driver need an update

1. Check VGA cable is firmly connected

2. Check/Adjust Screen resolution.

3. Update/rollback display driver.

the main problem may that driver need to update if dose not solve may be need to update bios because VGA diver not compatible  this case happens with me with HP Laptop

install display Driver the display driver need an update

Maybe the VGA Card need to replaced or something with driver u installed , 

first try to get the latest update of your VGA driver and reinstall it . if its still 

try to check the VGA driver if its not built in in other PC , if its built in maybe Motherboard have a problem with VGA

either the video card or the motherboard is the problem...