If you're using thermal paste, such as Artic Silver 5 or the one that came with your Zalman, give it a couple of days and the temps should come down. This is know as the "burn in" period, in wich the thermal paste melts and fills the microscopic valleys on the surface of both the CPU and the heatsink.
When I put my rig together and booted up, the CPU temp was 53º and a week later, it was 43-44ºC. Your milage may vary though....