only ways to tell reallyIronically, 99.9 times out of 100, a piece of hardware won't just flat out fail unless you actually do overclock it. People scared of voiding CPU warranties make me laugh though, it's not just going to blow up in your face on it's own.
"I can't overclock it becasue it'll void warranty!"...it's starts up, it runs, there warranty isn't needed, end.
There's no way in hell they can check anyway.
I wouldn't try to RMA something that I've borked through OC'ing. It just doesn't seem right.
How do you know it's the overclocking which killed it? It could have died anyway.