Okay, never mind, I found this thread, and finally read it through to the end (-:
All I can do now is confirm that the same thing happens with the 5960X on the ASUS X99 deluxe.
What tripped me up was that "AI Overclock Tuner" set to "Auto" and "CPU SVID Support" set to "Auto", the power is reported correctly, but changing "AI Overclock Tuner" to "Manual" while leaving "CPU SVID Support" at "Auto", the power is not reported correctly. If I read the above thread correctly, this means that CPU SVID support at that point has been disabled.
So confusing, having "Auto", "Enabled", and "Disabled" settings. Would be so much happier if the "Auto" setting would then tell me which value it intends to choose.