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Maximus Z790 Hero Q-Code 99 after power down

Level 7

This one's been bugging me for a day now and I'm stumped.

I powered down my pc yesterday so I could use the power outlet for another PC and moved the keyboard and mouse (both wired) onto the new other PC and also the monitor.

I did what I had to do on the other PC and then moved everything back to this PC powered it back up but it won't boot and hangs with Q Code 99.

Things I've tried:

1. moved the mouse and keyboard to other USB ports on the motherboard

2. Disconnected 1 component at a time until the pc is down to CPU, cooler, 1x stick of ram, keyboard, mouse, the M.2 windows 11 boot drive,

But it stays on Q code 99.

Does anyone have any ideas what to try next?


Customer Service Agent

Hello, @rebelcode 

May I ask if the situation you described happened after any changes were made? For example, updating the BIOS or connecting an external device
As the code refers to super IO initialization, in addition to checking the connections, restarting, and updating the BIOS, we suggest you try clearing the CMOS to see if the issue can be resolved.


Please also refer to the troubleshooting techniques in the [Motherboard] Troubleshooting: No Power, No Boot, No Display for further guidance.

Thank you.

Level 7

Hey mate, did you ever get this resolved? I’m having the exact issue after I powered my pc off to clean it. It now won’t start up and shows code 99.


Level 7

Hi _OJR_

No never got it resolved. No ASUS online resources helped at all. I ended up buying a motherboard from another manufacturer, installed it, moved everything over on to it and it's been working fine. Got a refund on the Maximus. It's a shame because I've been a fan of Asus and using their motherboards since 1998.

Thanks for the reply rebelcode.

Stupid this is, I left it overnight, unplugged from the wall, went to try it this morning and it booted fine. I have no idea what the hell happened but it's working again. Weird!