ah, skyrim... i noticed that while the phenom ii x4 had higher max fps...by 0.2 @ 3.5 ghz compared to the core i3, but the core i3 hit the 'somewhat-magical' minimum 30 fps mark (1 fps+ compared to ph ii x4). min. fps usually contribute to smoother gameplay. this is one of the cpu-bound scenarios i was talking about in my earlier post. the core i3 stands up to higher core counterparts quite well, at lower cost.
i find it kinda sad that ph ii has to be overclocked to outperform a lower clocked, locked core i3. because overclocking adds the cost of an aftermarket cpu cooler. it also drives psu requirements upwards as phenom ii is a 95w cpu (at stock) while core i3 is 65w. according to
this psu calculator, the ph ii x4 955 b.e. uses 155w at 3.8 ghz with 1.38v vcore (theoretical calculation). i used 3.8 ghz so that the ph ii x4 uses the extra mhz to gain more minimum fps over the core i3.
another factor is upgradability. from what i hear, amd is gonna focus on socket fm2 in the future and likely isolate socket am3+. amd became quite silent about piledriver after bulldozer release.
according to rumors, intel offers an upgrade to ivy bridge. depending on motherboard manufacturer's bios upgradability, sandy bridge core i3 can be upgraded to (i.e. replaced by) an ivy bridge core i5.
edit: however, both core i3 and ph ii x4 should offer playable fps (depending on personal preference) on present games. if one hits a performance ceiling, lower the details and get more fps out of any game.