So I've been mainly under-volting for lowest possible stable temps at stock since I put my system together. But part of the reason for that being that I haven't managed to get accurate temperatures when attempting any kind of over-clock. Specifically....

When I load into BIOS, my CPU temp idles around 40c. Which seems fairly accurate, as when I'm in windows it idles at about 32c, but when you factor in the sporadic temperature jumps from voltage/clock speeds shifting, the short term average temp is up around 37 or so....

Now where it gets strange, and problematic. In the above example, my bclck is set to the default of 100, and the core ratio is set to AUTO, showing as a setting of 36. If I change that ratio to ANYTHING other than Auto, (and don't touch anything else in the BIOS but that) even just manually setting it to 36, when I restart and go back into BIOS, my CPU temp is showing about 5c. The same thing happens if change the bclck to anything other than 100.

Even if the ratio is effecting something else that I'm not thinking of, I can't wrap my head around anything that would make that 5c be an accurate reading. And I can boot into windows like that, and it seems to run fine, except that my fan speeds stick at minimum so eventually it dies. I've considered just adjusting the fan temp ranges and playing around with it like that to see what happens, but that seems less than ideal and generally fairly pointless in the long run.

Is there something obvious I'm missing in some other setting? Has anyone else encountered this? All I've managed to find about temps is stuff about the AMD +20 degree offset, which seems like it may not be an issue anymore? I haven't seen my temps go beyond 55c.

Ryzen 1800x
ASUS Crosshair VI Hero X370
Mushkin DDR4 2666 4x8
ASUS ROG RX-480