Would be helpful to understand if unbalanced Core #0 is usual at idle or whether it suggests a potential problem in fitting or component. Will intend to overclock in 2013 (once I've got used to how much faster it is than my Q6600!!) would like to ensure I have a good chance of stable around 4GHz.
These temperatures are standard for what you will see. Core #0 is the first core that is being used the most. Core #2 is generally the hottest of all the cores when they are all running because it is is between the other cores and doesnt bleed the heat as well other other cores. With good cooling you shouldnt have a problem reaching well over 4GHz. I have my Intel® Core™ i5-3570K running at 4.3GHz at 1.2v.