Duke has a problem with his Windows 10 computer, which is restarting suddenly out of nowhere after about 10 minutes. Leo says that processors heat up really quickly, and if the thermal paste that ties the fan to the processor has dried up, it can easily start to overheat within a few minutes. There's software that can help show you if the processor is overheating. HWMonitor is the one to get.
Mike has an old Core 2 Duo Intel computer that's worked fine for 5 years. Now it's starting to shut down when he does transcoding of video. Leo says that overheating is likely the problem. When he's working on processor intensive actions, the chip can heat up, and PCs are designed to shut down when overheating in order to protect the PC. So it may be that he needs to clean out the case, but it may also be that the thermal paste has dried out and it needs to be reapplied.