 checking if the line period/frequency and refresh rate are still correct, the total pixel or line count when active plus front/back porch and sync pulse times are added together) may better reveal where and how the discrepancy was introduced, as the master clock and fundamental dividers are well known and provide an easy reference to compare any other claim against.VGA uses a DE-HD15 connector (often erroneously called "DB-15", in confusion with the larger, lower density Joystick/MIDI connector found on most PC soundcards and some ATX panels).This connector fits on the mounting tab of an ISA expansion card.