Dual Core activated in the BIOS!?!?! What are you talkin about???
There is no setting in the bios to activate/deactivate Dual Core in the BIOS.
Hyperthreading (HT) is NOT, nor has anything to do with Dual Core!!!
When you have a Dual Core CPU, HT is supposed to be OFF...
Unless it's an extreem edition CPU (840?) In that case, the 840 is the ONLY Dual Core with HT, then it could be on.
If you have an 820 or 830 CPU, HT has to be off, if it is on this not only could severly damage your CPU, but there will also be many stability issues.