Power supply noise.
Noise on supply voltages inside the chip can lead to all sorts of errors.
CPUs are CRAZY current bursty. This wide bandwidth low frequency rumble is crazy to look at on the various supply lines at the chip. While voltage regulators MOSTLY handle this noise, its much more of a impedance issue across a wide freq range below 100hz then a DC supply that feeds a chip. These supply lines need to be looked at as low freq AC rather then simple DC..
Motherboard makers typically follow "reference designs" for power supply bypass caps and regulation / current requirements. A "reference design" is the least expensive way that works. It is not the BEST way. So you see the same circuits and even board layout across various boards and board makers for a specific socket.
Each CPU is different in how its wired internally power wise. Each CPU has a different current spectra profile. This current spectra of course varies in realk time depending on what it is doing.
The amount of actual noise on the power input pins can be pretty impressive that it can work at all.
So its NO surprize that some CPUs, under some power conditions, running specific things, can glitch.
What makes this a more complex to engineer is that modern test equipment like a $100k Tektronix MSO scope really does not do well looking at noise. Digital scopes are all about statistics. Averaging. Glith capture. They are alll designed around capturing a SIGNAL and excluding noise. So when you get a truly random signal its much harder to look at using modern gear. To see these signals WAY better you gotta go back to the 70-80s and get a Tektronix 7904 analog scope. You can imagine modern motherboard makers and CPU designers dont have a restored 7904 on thier bench. BUT THEY SHOULD..
Plus modern engineers rely on computer modeling too much and soon AI..
So really the issue is instrumentation in R&D.
The solution to this issue tho is pretty easy. WAY WAY more super low ESR caps RIGHT at the CPU. So rather then a .1uF, a 33uF monolithic ceramic or more. Per pin.. Then a bit back from the socket, a giant tant cap, like 2200uF.. All this after the regulator and before the chip.
Now this issue might indeed be in the chip in how it handles the power lines on board. But cleaning up the power coming in can only help..
A digital system is really just a analog circuit running a few voltages that are on/off.. Modern engineers forget there is a VAST analog world that makes thier world go around.