ASUS Z170 stuck on boot_device error LED

Question

I've just bought this motherboard, added PSU, CPU, RAM and turned it on (using on-board video for now). Lights come on in turn indicating it's checking CPU, RAM, VGA and finally boot device, which it gets stuck on. No display on the monitor at all.

(Actually before it was stuck on RAM but I fixed that by moving it from slots A1/B1 to A2/B2)

This is a bit odd because you should be able to get to the bios config without any of these things. How stupid would that be if you accidentally turned off an option that allowed your motherboard to see a hard drive and couldn't get back there to undo it!

What could be the problem here? How do I successfully post with this thing?

Answer 1

I've found two solutions:

1. BIOS reset.

   Either find the jumper or remove the battery. I guess the board came with some options disabled and it wouldn't see my drives.

2. Plug a USB drive in. Try a few different ports though (see below)!

   This is absolutely retarded but I guess it makes the board think "oh, that's a thing I might be able to boot with later. ok, lets pass this test and allow the user to get to the BIOS settings."

I managed to reproduce this when I disabled some "CMS" setting in the BIOS, trying to make it post faster. Pretty sure it stopped it seeing any hard drives and so it refused to post.

Finally, some USB ports don't work until you're properly in the OS with the right drivers installed. Because reasons. For example, if you get to the login screen for windows and can't type, move the keyboard to one of the lower USB ports. DO NOT let windows search for the USB drivers when you download them, but instead run the installer. Otherwise it installs the wrong ones and your keyboard/mouse won't work even in safe mode. Could not recommend this board less for ease of use.

Answer 2

It sounds like your system doesn't POST. Reseating the RAM helped but didn't, so have you tried reseating the CPU? Also, do you have a mobo speaker? One of those would be fairly helpful right now.

I've actually had that exact problem happen to me recently on a Sabertooth Z97 (RAM led would light up, changed RAM slots, then the BOOT_DEVICE led would light up - I never got any video). My problem was a bent pin in the CPU socket (which I somehow managed to fix). The point here is things are not always what they seem when a computer fails to POST.

Make sure all of the power cables are properly connected - and you might also want to rule out a faulty PSU at some point. Weird power can do very, very weird things.

Given that the motherboard is new, your last option to consider is an RMA because it may very well have been dead on arrival. Are the other components brand new, too? Defective processors are rare but definitely not unheard of, and bad RAM could be a culprit there. You'll definitely want to test the components individually (with other known working parts) if you can.