Those temps seem pretty typical of many of the water cooled E8400's, with many load temps in the 60's and 70's...which seem surprisingly high to me.

Cooling, or even voltage increases seems to have little effect on Wolfdale temp readings. Some guys have removed their cpu fans completely and temps go up only slightly. I get the same cpu/core temps with the cpu fan on 800rpm, 1600 or 2250rpm...or with the voltage at 1.2v or 1.6v, makes no difference according to CoreTemp & CPUID Hardware Monitor. Intel's TAT does not work with Wolfdales.