Were you running an earlier BIOS rev which allowed other vCore, then flashed to latest f7d?
If so, that is your answer.
When microcode updates are released, stepping values are modified. Not always perfectly or to our liking. If your system is running stable, there is no need to update your BIOS. What rev were you running when it worked? That's where you should be if loading set up defaults or clearing the CMOS doesn't help.
Keep in mind that your memory choice can also effect this ratio. They might be tied. Not to say they should be identical, but if a profile for the RAM does not exist, it might affect the default vCore of the CPU. Setting your RAM voltage and timing manually in M.I.T might allow you to adjust the default CPU vCore in f7d.
