@Ryant01
Are you saying that the power cables, that connect to the motherboard with 24-pin and additional connectors, are NOT supplying the necessary power? If so, HOW are you determining that?
Or, are you saying that pushing the power button fails to turn on the PC -- which is no indication at all that power is not being transferred through the power button leads.
If the desktop simply will not turn on, that could be PSU problem (not providing power), a power switch problem (broken leads), or a basic motherboard problem -- NONE of which we are equipped to bebug from here.
For hardware diagnostics of the items mentioned, you would have to take your PC to a repair facility and pay them to run the diagnostics to see if the PSU is faulty and see what, if anything, they can determine about the motherboard.
I am a volunteer and I do not work for, nor represent, HP