on a modern CPU with billions of transistors does every single one have to be functional for the CPU to work or is there some redundancy if one fails?

Question

Additionally if my CPU has one transistor fail and yours is perfect, will yours be faster than mine?

In: Technology

Answer 1

Note that CPUs often come in a range of models based upon a single die. If there is a single defective core, the manufacturer may have the option as selling that chip as a lower model with less functional cores (or a lower clock speed) as opposed to the full flagship part.

Answer 2

There is redundancy so that if there are failing transistors found during manufacturing testing, the bad circuit block(s) can be removed from operation by blowing fuses. For a microprocessor, that is mostly limited to fusing out whole cores or large sections of cache memory.

If a transistor fails later on, during operation, you are generally screwed.

Your second question is harder to answer. If by “fail” you mean what we would normally consider a truly non-functional transistor, that doesn’t normally correlate with speed. But transistors/circuits don’t have to be “hard” failures; there are other failure modes that can lead to speed degradation.

*Source*: I’m a former microprocessor reliability engineer.