How many cores does skyrim use?

[diablo24life]

ive read alot of different answers. however i tested skyrim on full settings, i have an fx 4100 and ALL cores are being used while i play this game. all 4 cores are roughly at the 60-70% range of use. why are people saying that with there phenom IIx6 that its only using one of there cores? also people are saying that skyrim only uses 2 cores and it was designed for duel core processors at the time. then why are all my 4 cores underload? and how are some of the other people running quad and hex cores getting limited core usage?

 

[xtreme5]

minimum 2 cores and recommended 4 cores.