Well, it is either a glitch in MSI Afterburner or it is a faulty sensor on your motherboard. Seems you may be running your system not at stock settings? Overclocking?

I’d revert to stock settings for everything and see how things work out if this is true. Problem is, once overclocking damage via out-of-spec heat generation occurs once, damage may be already done.

It does sound like heat is an issue when stressing your system with BBC2.