: What are some signs your cpu has been damaged do to overclocking?
This depends on a few things. The first thing is to assume there is indeed damage caused by heat, which can result in 1) alloy diffusion of the N and P regions which results in a 'deformed' circuit over time and 2) internal part expansion/contraction on the chip which can lead to separations or cracks. These ultimately happen anyhow, given enough time at normal operating temperature, and this life time is called the manufacturer-specified MTBF (mean time before failure). MTBF is shortened by raising the heat applied and a few degrees can be significant. The Q10/2 method states that increasing a process temperature by 10 degrees will double a process reaction rate, i.e. if the MTBF at 100C was 300000 hours, then the MTBF at 110C would be 150000 hours. The range of such heat damage signs are from running normally to not working at all. The nearly normal condition would only happen if there was fault tolerant circuitry that was not itself damaged, and that the damaged area was, say, on board cache memory where a block could be de-allocated if found bad upon startup.
Concerning result 1), my experience dealing with alloy migration has been that digital circuits will either work or not so that the effect of alloy migration can be eliminated. If the circuit works at all, then it hasn't happened. Honestly, I don't think I've had a chip around long enough to see if this really happens, but I have seen electron microscope images showing an aged chip compared to a new one. The aged one looks like a mars landscape a bit while the new one is clean.
Concerning result 2), the more common problem I have seen is intermittent problems where a cold spray on a questionable chip proved or disproved that the chip had a 'cold' connection somewhere internal (a small separation). As a technician in the DOD, I have seen this approach: Get the system with questionable CPU to run until a problem occurs, then spray a cold spray on the CPU and see if the problem goes away. Or, if the problem causes a lockup, then start the system while spraying the cold spray as needed to keep the CPU cool. If the problem is not seen, then you can assume a 'cold' connection. A big assumption here is that the rest of the system besides the CPU is not the cause for any problems. If you can use an identical motherboard as well as other components, you can rule this out.
Other than just waiting for the numerous possible signs of heat damage on a system that does not have any known problems, use the method that many electrical engineers and technicians have used which is the cold spray method to exhibit or bring out the heat damage on a system that is known to have a problem. Other than that, the heat damage could only be seen with an electron microscope.