BIOS reading is CPU Tcase, not the temps of the cores. Going by your Speedfan temps Tcase is probably "Temp2", you can do a load test to easily find the one that rises the most. In other programs such as Everest Tcase is labled as CPU, and for M0 steppings Tcase is usually 7-13c below core temps with the exception of exceeding 16c delta when heavily overclocked or volted. You are using an old version of Speedfan and should update to 4.34 beta 38 which is the latest and can be found on my Filefront space here: http://files.filefront.com/sfbeta38z.../fileinfo.html
Extract Speedfan.exe into your Speedfan folder and thats it.
Speedfan's latest version 4.34 beta 38 will also need a +15c offset to both cores.
Intel rates their thermal spec on Tcase and NOT core temps. Thermal spec for your CPU is 72c Tcase, so at that temp your cores will be about 79c-85c which is ok, we just don't want to go above thermal spec.