All the fans (CPU, system fans, PSU) keep running after I shut down Windows 8. This is also the case when I put the system on sleep or hibernate. Sometimes the fans run at full speed after shutdown and sometimes they run at lower speeds. This has nothing to do with high temperature. All the parts are new and it has been like this since day one. The motherboard is a Gigabyte Z87-HD3

I have tried disconnecting the power cable, holding the power button (to "empty" the power) and disconnecting/reconnecting the fan cables.

EDIT: Powerled is also on after shutdown/sleep/hibernate