Why would the BIOS utility be returning the socket sensor? Shouldn't it be returning the temperature from the CPU itself?
For my MIVE-Z, the BIOS utility that operates within Win7 reports the socket temp but labels it the CPU temp. I have no idea why.
I confirmed this when I was curing my Indigo Extreme, a process which requires you to run a CPU stress tester like LinX while disconnecting your fan on the HSF so the CPU heats up to 98C and throttles.
Watching temps with RealTemp while watching my CPU clocks with CPUz, and simultaneously monitoring the reported CPU temp with my Asus BIOS utility showed that RealTemp correctly identified the CPU temp (CPU started throttling right when RealTemp said it was at 98C) but the ASUS bios utility was reporting the CPU temp was a mild 50C.
In theory there is no difference between theory and practice; however, in practice there is.