I should have been more specific. It's not needed to be supplied by the PSU to the A4000. If you tell him he needs -5V from his ATX PSU that is wrong.
-5V on the A4000 is generated from -12V on the motherboard. So it is not needed to be supplied by the ATX PSU he has.
Ah!! Yeah, there are two topics in this thread... One is on the A4000 PSU replacement, which yeah totally, the A4000 PSU doesn't supply -5v. Which makes it much easier to use an ATX PSU with an A4000 as long as the PSU can supply enough current for the A4000.
The other topic that was brought up was an A3000 ATX PSU adapter and how modern ATX PSUs don't supply the -5v that the A3000 needs. My previous comment was directed at the A3000 and it having -5v from the PSU.