B550M Pro4 High CPU Temps

what are your temps whilst in Windows?

It isn't a bug, it's because the BIOS utilizes a single core at full frequency and
voltage the entire time you are in the UEFI. The size of the BIOS chip means there
simply isn't enough space to incorporate power saving of any kind. The end result
is a single core runs at near 100% load the entire time and gets hot.

If your cooling solution is keeping you under 80c in the BIOS then you are likely
not going to have any thermal issues in OS.

You are not the only one that was bothered by the high temps in the UEFI
I did a lot of research into it and asked some of my industry contacts about it.
The old text based BIOS setup was a lot less demanding and showed temps much
closer to what you would expect at idle in OS. It was also a lot less versatile.

Also bare in mind that I am talking about AMD in this instance (under 80c), most BIOS temp
monitoring monitors the tCTL sensor which is meant to be offset by between -10c
and -27c depending on the CPU model (threadripper is -27c). In practice this
usually means that if you are seeing 65c on an AMD Ryzen based system you would
likely see 55c on an intel board. Feel free to look up tCTL in more detail if you
like but in a nutshell, it exists to conrtol (CTL) the fans, by the fan controller
thinking that the temps are higher than they are it responds much more rapidly.
I suspect this is a limitation of fan controllers that were never designed to
manage such rapid heat fluctuation, more cores heating up together means much
sharper temp spikes than on older dual and quad core setups that were the norm
not that long ago.

I imagine new controllers will emerge eventually and the tCTL workaround will
be abandoned but I doubt it is a priority as the current method works very well
and doesn't cost anything to implement vs designing a new IC.

Edited by Xaltar - 30 Jun 2020 at 10:26pm