I found it always bit clumsy that when I want to search case sensitive/case insensitive, I had to flip the 'ignorecase' option.
As it turned out, there is much much simple way: an 'ignorecase' override, right in the search pattern itself. Here it is.
Case insensitive search (as if 'noignorecase'):
Case sensitive search (as if 'ignorecase'):
/\cPORTFirst would find only "PORT" while the second would find also "port" and "Port". Easy peasy.
See more at :h /\c and :h /character-classes.
P.S. Blogspot seems to be too devastated by the