X399 Fatal1ty Bios HW monitor bug?

There seems to be a discrepancy between the CPU temperatures in the BIOS. In Advanced mode under the HW monitor tab, CPU temp for me is saying 52.4 at the moment at idle and that cannot be right. So I switch to easy mode and that CPU temp reading in the upper right is 32c which does sound right to me. Is this a bug in the bios? I am pretty sure this was happening in the other bios I have used 1.30 (which came with my board) and the 1.60 I used briefly.


Edited by LurkerLito - 25 Sep 2017 at 7:50am

LurkerLito wrote: There seems to be a discrepancy between the CPU temperatures in the BIOS. In Advanced mode under the HW monitor tab, CPU temp for me is saying 52.4 at the moment at idle and that cannot be right. So I switch to easy mode and that CPU temp reading in the upper right is 32c which does sound right to me. Is this a bug in the bios? I am pretty sure this was happening in the other bios I have used 1.30 (which came with my board) and the 1.60 I used briefly.

As I've tried to explain in other threads, including one of yours, there are multiple temperatures reported by Ryzen processors, called Tdie and Tctrl. For some Ryzen 7 processors, they are different, for others they are the same. Since you seem skeptical about it, I'll let AMD explain it:

https://community.amd.com/community/gaming/blog/2017/03/13/amd-ryzen-community-update

Pretty much a semi-explanation IMO. The use of Tctrl is not clear, although I have a theory about it that I won't share at this time. IMO, Threadripper would also have the 20° C offset from Tdie, and report a Tctrl temperature. Finding information about this is frustratingly difficult.

The temperature reported in the UEFI of my ASRock X370 Killer SLI/ac with a 1700X at 3.9GHz is normally in the upper 50's C or more. None of the CPU power saving options are active when in the UEFI/BIOS, as well as none of the Windows Power Plan processor state controls. So the core speed is at its maximum, regardless of load. Only one CPU core is in use, no core or thread scheduling in the UEFI/BIOS. Note the VCore reading in the UEFI compared to Windows.

So while I wanted to think the HW Monitor temperature is Tctrl, with its 20° C offset from Tdie, I'm uncertain. I've seen the same behavior, a higher CPU temperature in the UEFI than in Windows with earlier and current Intel processors (Haswell, Broadwell, Skylake, Kaby Lake) too, for the same reasons, and possibly others.

If I then go into Windows, run HWiNFO64, check the Tdie and Tctrl readings, separately listed with my board, and I see Tdie as low as the mid 20C with the CPU at idle, but of course Tctrl at the same time is mid 40's C, perfectly offset by 20° C.

In your case, between EZ Mode and Advanced, the perfect 20° C difference sure looks like Tctrl being used in Advanced mode, and Tdie in EZ Mode. The reason(s) for the difference is unknown to me.

An interesting test is, if you don't have things configured like this to start, in the UEFI/BIOS, disable the Cool N Quiet, C6, and Global C State options. Then boot into Windows, and set the Power Plan to High Performance, which should set the Minimum Processor State to 100%. Then check the CPU temperature. Compare that with all the CPU power saving options enabled, and the Windows Power Plan set to Balanced. Don't use the Ryzen Balanced power plan for this test.