"Temp5" showing as 90C on ASUS ROG H370-I



Testing HWiNFO for monitoring for VPS/home servers, when I notice in the motherboard temperature on one of them... ASUS ROG Strix H370-I, the "Temp5" is 89-90C. Everything else is below 32C... It's a mini-ITX board/case, with an AIO cooling the processor. CPU - 31C, PCH - 32C, Motherboard - 32C...  then out of nowhere, Temp5 90C!

Is this just a glitch or something? I notice on my main rig which is also an ASUS motherboard, the "Temp5" is reading only 9C, which is impossible as that's far below ambient temperature. I'm guessing this Temp5 doesn't exist on ASUS motherboards? Or is my mini-ITX frying, and my 8700k freezing as I type this?
That value is certainly invalid, a result of a not connected floating sensor.