I worked on validation at Intel and the primary source of faults over time is electromigration in the lower metal layers and our failure rates went out to 7 yea

I worked on validation at Intel and the primary source of faults over time is electromigration in the lower metal layers and our failure rates went out to 7 years (and there are multiple scenario %-failure curves in that window), and we dialed that back during the war with Athlon. Other sources of error are bit failures in sense amps in low-voltage SRAM circuits. Hitting reliability above 105 C Tj was really really really expensive for the big die sizes of Intel CPUs in the 2000s. Claiming the crown for low-yield high-performance CPUs required relaxing a lot of failure rates. However, intel was so paranoid to begin with, it didn't lead to massive failures but remember that industrial consumers have much more rigid requirements around reliability than gamers.