0x99 Super IO Initialization
Page 37 of the manual.
IO means anything connected to the board by any interface is not initializing.
Have you just built the system, then it is saying a device is not connected properly.
Or there is a lack of power to a device causing the IO error.
Input Output error. It cannot communicate with a part or device through its slot/ bus interface. Or due to a lack of power.
Check all the components are seated flush and level and aligned in parallel with Pci-e slots ect.
For example the weight of a graphics card can pull on a Pci-e slot.
So the contacts from the slot to the finger connections of the card don`t contact tight on one side of the Slot to the card.
Sometimes you have to unscrew and level it up. So it is more parallel with the pci-e slot.