When I get a computer problem like that, my first suspicion is the CPU or motherboard. Power supply comes last, but is usually cheaper to replace than a motherboard or CPU. Seeing as he tried a new motherboard, Iwould have to say it is the CPU. I have never had a computer fail to start because of the USB ports not getting power.

Did he have to buy the PSU and motherboard that he tried? Is he going to have to buy a new CPU? Added together they can start to hurt the hip pocket.

Mark