On bios is about 65° but in the same situation is about 30° on HWMONITOR or others.

Is it a bug?

Ooh, my CPU is 1700x install on X370 PRO gaming

Dear -BrOLy-,

Greetings, this is ASRock TSD.

The BIOS temperature source of Ryzen CPUs is reference to the CPU tCTL which included +20°C offset according to AMD official announcement.

 

The CPU temperature source in third party like HW Monitor is reference to the true junction temperature, so it may lower than the temperature which read from tCTL.

 

In addition, the BIOS environment does not include driver to allocate the CPU resource, so it is normal that the CPU will run at full speed and the temperature under BIOS will higher than the OS environment.

  

For further information, please refer to AMD announcement as below link,

http://community.amd.com/community/gaming/blog/2017/03/13/amd-ryzen-community-update" rel="nofollow - https://community.amd.com/community/gaming/blog/2017/03/13/amd-ryzen-community-update

Thanks!

All the best,

ASRock TSD

Edit - 27 is for my TR 1950x, 20 for the 1700x mentioned in the OP

There are 2 (3) temperatures that get reported with regards to the CPU.

One is the CPU die temperature, the temperature of the chip itself.  This one has 2 possible readouts one is true, the other is 20°C higher than it should be.  You'll find this temperature referred to a Tdie.

The other is from a sensor on the motherboard, near/in the socket. This one fluctuates less than Tdie because it's getting residual heat, not direct heat.  This is often referred to as T-socket.

On the 1700x and 1800x the Tdie reported by the hardware is actually 20°C higher than it should be.  This offset is handled by software but isn't really handled in the BIOS/UEFI.  When setting up fan profiles in BIOS, just add 20°C to the target temps, no biggy.  It's not an unusual thing, this offset, I had it on my old Core2Duo Intel CPU too, but there never seemed to be a completely honest answer from Intel as to what this offset actually was - AMD stated it pretty close to the beginning.  Bear in mind, the temperature is derived from an internal calculation based on TjMax, or the delta from the maximum.

I set up my UEFI to control CPU fan speed, rather than have software do it.  I've configured all of the temps correctly, and it works just fine for me.  Some trial and error of course, but the fans are going nuts here, and temps are always pretty low.

Tdie = actual die / chip temperature.

Tctrl = Tdie + 20.

'T-socket' = socket temperature sensor on motherboard.

I didn't like T-socket because it took too long to ramp up, and the CPU was getting toasty, but the fans weren't kicking in quick enough.  Once T-socket reflected a higher temperature (due to sustained CPU load), it would take a bit longer for this temperature to drop, whereas Tdie had already dropped, as the load had gone.

In a perfect world we'd use Tdie as our temp source (or just offset target temps by 20 from Tctrl) and use some hysteresis to smooth the fan adjustment out.

As the Noctua fan I have makes more noise when it's changing speed than when it's up to speed, I have set the fan profiles to work in steps rather than as a ramp.