To be fair, it can well be that some sloppy OEM drivers take too many assumptions on reserved bits in registers (which the new microcode may be legitimately cha

To be fair, it can well be that some sloppy OEM drivers take too many assumptions on reserved bits in registers (which the new microcode may be legitimately changing) or on undocumented timing side-effects related to some instructions (which the new microcode may affect, being that the root problem in the first place!). These symptoms are also the classic ones you get when you install an OS on a new-generation, well-functioning CPU.