I just OC'd my i7 4770k to 4.2 using the "CPU level up" option in Asus's bios settings. I realize this is not the best way to OC but I habe no experience manually doing anything.
Now, my idle temps are 28c.
When I stress the system with a torture test for about 20 min I peak at about 68c average, which seems a little high for 4.2??