The best way for me is to load prime 95 with ht on and use half of the threads so on my 920 I ran 4 it does not load it 100% but heats it equally across the ihs and has less a likely hood of crashing during the reflow. That's just the way I have found to work best for me, other may have different opinions. As far as my waterblocks I tighten them down all the way down but loosen the bottom two a couple turns to help "direct" reflow across the whole chip and re-tighten them after the reflow. Again these are just the ways I have found to work best for me, others may have different methods.