Looking at your 2nd screenshot, you have "Mobo Temp3" selected, and the fallback temp for it is set to 50.00.
As the problem is intermittent, I would guess Open Hardware Monitor is not sending updates at times, and AQS is displaying the fallback temp when this happens.
You could use the HWiNFO program to drive your AQS Software Sensors instead of OHW.
HWiNFO is free and generally more reliable.