I know it may sound stupid but, will US hardware work on UK stuff. So say if
I imported an amd socket 939 processor and mobo and plugged them into a UK
power supply. Would they fry? I assume not because they both work on 12v
Any internal component should be fine, as it will be powered by your PSU
output voltages, which are (I hope!) standardized throughout the world.
Anything with it's own power supply *may* be a different story.