Originally posted by Hippie_Tech
If memory serves, the whole 5800 series used fairly standard parts. I've switched out power supplies in a 5838 (Athlon) and a 5834 (Celeron). Both of them took a standard Antec ATX power supply without a problem. I think the only thing in those machines that was proprietary was the case to motherboard connector (one single connector rather than individual connectors for HD LED, Power, Reset, Power LED, etc.).
AthlonDave: this isn't one of the blue faced ones. It's the beige ones with the door at the top and the IO panel at the bottom.

Yes, the mobo connector is proprietary