17″ Monitor not functioning well

Hi Experts,
I have a 17" monitor that's 5 years old and have been facing different issues. Some times there is no display and some times there is a lot of lines which effects me from working.
It display looks like shuttling up and down which happens when there is low power.
I have checked these.
1. Power supply watts is fine
2. Earthing is fine
Thanks in advance for the help
