You could also just run two instances of Orthos and set the Affinity of 1 instance to CPU 0 and 1 and set the other instance to CPU 2 and 3
Thats what I did to max all my cores out. I settled for 3.15Ghz eventually simply because I can run that at a very low voltage and when its not enough I am sure I have plenty of OC room left to go
Also, if your temps are that high only maxing 2 of 4 cores... once you max all 4 cores your CPU is going to blow up... lol. Id take it back quite a bit and work your way back up!