External monitor showing greenish shadow
Determining the cause of display issues is generally a basic troubleshooting task, performing substitution on components until the faulty component is determined:


replace cables (you've already done this)
use the monitor on a different computer
use a different monitor on the same computer


In this case, you've used a different monitor on the same machine and found that when using the same cables, the different monitor is not showing the color changes, therefore the monitor has the issue.