How can you tell if a cpu is used?

[JamesAnderson]

Amd Phenom Ii x4 Quad Core Cpu £70
This has been use for 5 mins, works perfectly and is in perfect condition, comes with the box, fan, cpu, stickers, instructions etc, pick up or delivery available.

Thanks.

Well thats a second hand phenom I've found, but How can I trust the person who says he used it for 5 minutes, is there a test I can do, or a tell tale sign :/

Thanks