Mutang running which overclock ? I would opt for a fan on the NB and some good ventilation in ya case. I'm using 3 ghz as a 24/7 setting , once I start to bench and do more fun stuff I screw it up to 3600mhz and more...

what hardware are you running ? 39°C idle seems pretty high to me as the cores are already in the mid 40's then. What are the opt 1-4 ? temps maybe NB SB and PWMs ?