AMD today announces the details on how the temperature sensor built within the R7 1800X and 1700X works. This is due to Ryzen CPU owners reporting high temperature results with the said CPU models. Here’s what they said.

Specifically, the AMD Ryzen™ 7 1700X and 1800X carry a +20°C offset between the tCTL° (reported) temperature and the actual Tj° temperature. In the short term, users of the AMD Ryzen™ 1700X and 1800X can simply subtract 20°C to determine the true junction temperature of their processor. No arithmetic is required for the Ryzen 7 1700. Long term, we expect temperature monitoring software to better understand our tCTL offsets to report the junction temperature automatically.

So basically, both the Ryzen 1800X and the 1700X shares a +20°C offset. Meaning, if your model reports a 61°C at the UEFI, then it’s most likely 41°C. The table below from AMD serves as an example on how the temperature control (tCTL) sensor can be interpreted in a hypothetical scenario where a Ryzen processor is operating at 38°C.

Product Name True Junction Temp (Example) tCTL Offset for Fan Policy
Temp Reported by tCTL
AMD Ryzen™ 7 1800X 38°C 20°C 58°C
AMD Ryzen™ 7 1700X 38°C 20°C 58°C
AMD Ryzen™ 7 1700 38°C 0°C 38°C

AMD did this to ensure a consistent fan policy across the available AM4 Platforms. Providing an accurate distance from the actual Tjunction Max of the CPU. Still, I expected motherboard vendors to roll out precise readings since launch, so this could be a hindsight from AMD and or their partner. Requiring temperature offsets rather than working out a tailored solution for each models.