Re: overclocked CPUs are more likely to make a Windows PC crash
Well, not strictly true.
Most CPUs are designed to run at a certain speed. When a particular member of a chip family is first spun, chances are only a small percentage of the silicon will run reliably at the full design speed, but many more will run at a fraction of that speed. So they are marked with the slower speed, and sold as slower chips. But they were still designed to run that the higher speed.
Manufacturers put pretty much every CPU through some testing, starting at lower speeds and increasing it until the chip fails to execute something correctly. They then stamp the chip with the last speed that worked sucessfully, and then move on.
What overclockers do is that they reason that when a chip runs above it's tested and rated speed, the cause of failure is probably due to heat, so they put a better heatsink on the chip, and then ramp the speed up above the rated value until it fails, and run it at the highest speed that it functioned correctly. The better the cooling, the higher the clock speed you can run it at (that is why some HPCs have direct water cooling of the CPUs, and why people like Amari [I believe] used to sell an actively refrigerated PC at one time).
Unfortunately, another aspect of heat damage is that it can be cumulative. This is, I believe, what Microsoft are trying to say. This aspect has a name, and it's called 'cooking' the CPU. Once you've cooked it, the chances if it running reliably at the same clock speed (or even at it's rated speed) is seriously reduced.
The most obvious case of this I saw was Throughbred AMD Athlon XP2600s (that was the highest speed Throughbred cores with 133MHz FSB, faster Athlon XPs were Barton cores with an FSB of 166MHz). These were actually clocked with a multiplier at something like 2.06GHz, but over time, even if you did not overclock them, they stopped performing at their rated speed. You had to gradually step down the speed to keep the PC stable. Replace the CPU, back up to full speed, at least for a few months. I went through three or four before I realised what was going on, and this happened even with overspec'd heatsinks and fans.