Power supply *has* been integrated at source...
Probably my favourite of quite a number of classics from a year or two of working on a helpdesk when a student:
User: (on phone) My PC won't turn on.
Me: Ok, have you checked that it's plugged in?
User: Yep, it's definitely plugged in - and I checked both ends of the cable.
Me: Hmm... Right then - are you pressing the correct button - the one on the box under the desk?
User: Yes, I've pressed it. I shut my PC down every night so I know which one it is because I have to turn it back on every morning.
Me: Ok, and there are no lights on the box when you press the button?
User: Nope, no lights.
Me: How about the monitor? Any lights there?
User: Nope, none at all.
Me: Ah, this is starting to make sense. Which floor are you on, exactly?
User: The third.
Me: The one with the power cut, then.
User: ....