Odds are all those components fell victim to a crappy power supply.
In all my years of building PCs and fixing them, almost always failure comes from one of two things, a crappy power supply, or overheating, from overclocking, or just dust bunnies.
I see it all the time, guys build bad ass gaming rigs, then put a 30 dollar power supply in it after spending top dollar on great components, and then wonder why it all failed.
That being said, all the pre-made PCs out there from companies like dell, etc. etc. You get a crappy power supply by default, good speciality makers would never do that since they know how critical the power supply is.
Mike