In my job I'm using a CM2009 IC between precise VGA controller and VGA output connector. It really is pointed out within the datasheet for this IC which i can use EMI filters on HSYNC, VSYNC and DDC channels suitable right after IC and ahead of VGA connector. Nevertheless there https://trentongasiy.activoblog.com/32610239/detailed-notes-on-emc-vs-emi-filter