Windows 7 Windows 7 pro not detecting dual core but bios is, tried everything

Have a e6600 dual core, evga 680i board, 4 gb ddr26400, gtx260, win 7 pro upgraded from vista. I have looked all over and tried almost everything. BIOS detects dual core as it allows me to enable or disable the second one, and intel proc id tool detects 2 cores. However, windows 7, and any other programs like cpuz and core temp report one core. Under device manager only one core is listed under processors, and under computer it says ACPI x64 pc or something instead of acpi multiprocessor. MSCONFIG only shows one core to be enabled/disabled. Have done repair install, full install, reformat install and still only one core shows. Tried easyBCD with core=0 to try and reset, and nothing. BIOS is up to date (P33), reset bios settings and even ESCD reset. This all started after power cut out randomly. At first, windows would not boot, but did mbr repair using a win 7 home disc and it booted. Few min later comp felt sluggish so looked at cpu usage and task manager and found out about only one core detected. One graph/cpu is already selected as it is the only option.