No it shouldn't dry up. Part of what makes a good thermal paste is the fact that it stays viscous for a very long time, thereby making it more effecient at transferring heat. To be honest, I don't know how you're supposed to make ramsinks stick...
I currently have one 80mm side fan set up to blow air onto my spark7+ cooler. There is a sort of makeshift plastic shroud between the fan and the HSF that extends from the side of the case flush up against the HSF grille. Now the spark7 has a variable fan speed, and goes from about 1500 rpm to...