|After review I have additional questions. |
Is you computer currently fully assembled and all items connected?
Did you clear the CMOS while the computer was unplugged?
Do you have the PS/2 keyboard connected to the purple port?
I asked about the front ports because those are connected by wiring to the motherboard. Some USB ports in the back can also be connected by wiring to the motherboard. The problem is they can be connected wrong. No harm comes until a device is plugged in. The rear ports would be located lower in the case where there are removable plates.