heat sink installation

Is it unadvisable to install the heat sink on a new motherboard before it is installed in the case? If so why.

 

It's easier to install the heatsink outside the case except if it hides the screwholes that fasten the mobo to the case, then you have no choice. If you have big one then install the backplate first, install the mobo and install the fan. I've got quite a few cuts from the sharp fins.:-D

 

Thanks for the info. I just wanted to make sure I installed everything properly. Someone from ehow.com advised against doing it that way, but I though it would be easier to install everything outside the case, that way I could be sure everything works before installing in the case. Thanks again, and have a good weekend!