I suppose this thread is dead but it describes my issue perfectly. Am I to understand from this discussion that it is in fact not an issue after all? I'm getting 122-124C Motherboard temp as well. With Speccy and HWiNFO64. Thought it could be because I was using Handbrake to do some video encoding, but that's stopped. I recently opened the case for a "squizz" lol, but maybe I'll hit it again.
System specs link below, but I attached as well since that'll be deleted after 30 days.
http://speccy.piriform.com/results/NgY1vxMj4cagmAonnBeDbeh
DESKTOP-2S7JO6I.speccy