Matrox Mystique G200

I have a few of these cards that all are a little bit different:
a) this particular card has SDRAM and a heatsink fitted.
b) almost identical but without heatsink and equipped with SGRAM.
c) a third one, again without heatsink but equipped with SDRAM.

I have a fourth one that is virtually identical to this one. I haven't tested and benchmarked all different models. Usually cards with SGRAM from the era are slightly faster because SGRAM has faster access times. I have no idea about the clock frequencies yet. I wonder why some are fitted with heatsinks... higher clocks maybe?