I've found the same issues with the Maximus, since using the new OCCT Beta.

I can use OCCT 24/7 if I keep cold air blowing directly over the vregs, mosfets and caps around the CPU. As soon as I take that extra airflow away it lasts a few hours MAX before crashing and Folding can crash within hours too... Right now with window open and case temp of only 23*c (temp sensor seems out, it's about 10*c by the window...) I can Fold/OCCT/Prime/Game as much as I want, but seeing as I don't like my hands turning blue I keep the window pulled shut. This instantly increases the temp in the case and then I lose my stability...noticably with voltages going, then crashes/reboots!

What particular parts would people recommend for extra cooling/heatinks to be attached? I'm building a caseless testbench so I'll be able to get closer in to the motherboard and use my 'OPT Sensor@ temp sensors from my Striker Extreme on the Maximus to read these temps correctly around the NB and CPU area!