Hmm... Myself and a few others had the same or a similar problem earlier this year with a Bios for a different motherboard, a Rampage VI Extreme Omega. The then new Bios had our CPUs stuck at the boost speed, and so the clock speeds were stuck at that level and our idle temperatures were in the 70s C with them up into the 90s C under load. We reverted to the previous Bios and the problem went away. Good luck. Oh, and thanks big time for relating here how the new Bios worked out for you.
I doubt this would help, but another poster said to make sure to install a new Bios with your Bios set to default settings.
Also, just curious about your CPU model. If you would be so kind as to post your system specs, that would rock. 😄