Capital letters or non capitals doesn't change panel type...Does all S-IPS generate more heat than S-ips?
And like said amount of consumed power depends mostly on backlight/its brightness which is independent from type of LCD matrix.
(in fact because of structure LCD display's backlight has to produce many times more light than what escapes from white picture)
Power supply is other heat producer, but I would think they all have quite similar efficiency.
So probably biggest factor for temperature of display is design of casing, it it's such that air circulates well heat doesn't built up but if it doesn't have good cooling then heat gets stuck inside casing and temperature of casing has to rise until balance is achieved through increased conduction to air and radiative cooling