I never killed a component totally to where it was unusable, but I have scrambled a hard drive or two when the PCI bus went too high. Since the IDE controllers run off the PCI bus, you can have trouble if you take that too high, I totally learned that one the hard way...LOL 😱
Thank goodness for my ASUS A7n8x mobo, it is AGP & PCI locked. FSB changes only affect the RAM and CPU, otherwise I might be overheating video cards and scrambling hard drives left and right...