Over temp most likely cause is that the HSF is not seated properly. Need to reseat which req removing Thermo coumpound and reaplpling.
Some pointers on Installing Intel HSFhttp://www.google.com/#sclient=psy&hl=en&q=how+to+install+intel+cpu+fan&aq=0&aqi=g4g-o1&aql=&oq=&gs_rfai=&pbx=1&fp=c9f200e8d6433b2a
That said, The stock intel HSF is crap. A number of people have problems getting it seated properly (Not really the HSF, it's the pushpins) and the Stock HSF is at the bottom of the list when it comes to performance.
On Memory. (1) always run Memtest 86 from a bootable CD (Free down load) BEFORE attempting to install operating system!! It's an ISO so do not just copy iso to cd, bust use the "create an ISO".