In my undertaking I am using a CM2009 IC between precise VGA controller and VGA output connector. It's stated from the datasheet for this IC that I can use EMI filters on HSYNC, VSYNC and DDC channels appropriate just after IC and in advance of VGA connector. Even though there https://garrettnvxvt.weblogco.com/31273056/detailed-notes-on-emc-vs-emi-filter