Hmm. If you could list all your hardware in detail, i could see if there's something that catches my eye.
Enabling XMP usually raises some secondary voltages like IO and SA2, but that should only cause up to a 10W increase in power draw overall, so it's nothing that should make the temps go wild.
I talked about that here before, for example,
https://forum-en.msi.com/index.php?...-but-now-xmp-doesnt-work.367744/#post-2083048
I haven't seen what the MSI BIOS raises those voltages to when you use four dual-rank modules, which is the most challenging setup for the memory system, as i describe in
my thread about RAM.
It would be interesting to know what voltages you have active now (you can press F12 to make a screenshot in the BIOS and save to a FAT32 drive, you might wanna convert BMP to PNG later).
The behaviour of the board not being able to recover from failed OC unless you force-flash it is unusual indeed. MSI boards are usually renowned to recover pretty well from failed OC attempts, meaning you can often get by without a CMOS Clear even. But this... weird.
Another weird thing. Copying a file to external USB3 HDD spikes all cores to 100%?!?
It can be something like the antivirus checking the files. Full load is easy to reach, the task manager is quite "dumb" and doesn't show what kind of "effort" the CPU is using for the load. You can have vastly different power consumption with different types of full load. This is visible in
HWinfo64 , by the amount of CPU power draw. If you open the sensors and double-click on CPU Package Power, it will show a graph that tracks CPU power draw over time, or you can just keep an eye on the number.