I recently replaced the psu on my old pc. Everything appears to be fine with the exception of the top two usb ports in the I/O panel on my Asus Z97 motherboard. Everytime i shut off my pc for an extended period, i get the message at boot up that no keyboard was detected. I plugged my mouse and keyboard to the other ports and they work fine. Now, whenever I go to the bios and load optimal settings and reboot, the top two USB ports start functioning again...until I turn off my pc for an hour or longer.