Your intensity dramaticly affects the stability of your rig..  So does temperature.  If its stable at the lower intensity I suggest staying there.. However if you have a card where you can lower the voltage on it, I will tell you that it dramaticly decreases heat and increases stability.  Defaults on my msi 7950 voltage were 1.188 and I run them at 1.050 with a higher intensity now.  A well tweaked bat file makes all the difference as well as good hardware.