anybody with experience in changing a hashboard?

I think that I need to apply some greese between the hashboard and the heatsinks.

what about http://www.arcticsilver.com/as5.htm.  is it ok ? I'm a little bit worried about the cycles needed for optimal use.

quoting from their website:

Important Reminder:
Due to the unique shape and sizes of the particles in Arctic Silver 5's conductive matrix, it will take a up to 200 hours and several thermal cycles to achieve maximum particle to particle thermal conduction and for the heatsink to CPU interface to reach maximum conductivity. (This period will be longer in a system without a fan on the heatsink or with a low speed fan on the heatsink.) On systems measuring actual internal core temperatures via the CPU's internal diode, the measured temperature will often drop 2C to 5C over this "break-in" period. This break-in will occur during the normal use of the computer as long as the computer is turned off from time to time and the interface is allowed to cool to room temperature. Once the break-in is complete, the computer can be left on if desired.


Caution:
We do not recommend using Arctic Silver 5 on the older slot type Intel Xeon processors with large multiple square inch CPU to heatsink interfaces. The huge contact area and large gaps between the processor and the heatsink require a thermal pad or thick mesh-reinforced paste. Arctic Silver 5 can be used on socket type Xeons without a problem.



Thanks!