LONG delay while booting

I don't THINK this is a Windows 10 thing, so...

ASUS X99 Deluxe, Windows 10 Pro, 32 GB memory, AMD 5700 XT graphics...

For the last couple months, when I boot the system is posts (presume post is that time when the system wants you to press DEL to go into the BIOS). Then it sits there for 80-90 seconds. Then it boots.

A bit more information. If I do a boot starting from having the power supply shut off (cold? boot), it SEEMS to boot fine. If I do a normal shutdown/restart while in Windows, it sits. If I hit the reset button it boots. What I've taken to doing is when I do a "normal" shutdown/restart, when the "press DEL" screen shows up I hit the reset button, and it boots fine - no extremely long delay while it sits there...

It displays a 99 while sitting. ASUS says this means Super IO Initialization. I've read a bunch of discussions various places and they all have "THE FIX", which, of course, haven't worked...

One discussion insisted if you get this code the motherboard is bad and should be replaced. I don't think so, since it only happens when doing the shutdown/restart from Windows.

One discussion indicated it was a motherboard connections - pulled all the plugs, reconnected, reseated the memory, made no difference. The other day I removed all the hard drives except the O/S SSD and it still did it. Put them back in 1 by 1, no difference.

Another discussion said to replace all the SATA cables to the hard drives. So I did that. Nothing. No change.

I replaced the graphics card - not because of this, just because it needed it... No difference.

I've got 2 monitors, 1 DP, 1 HDMI. Removed the HDMI one, no difference.

I think I'm out of IO things to unplug.

Ideas?

Yeah, I read a BUNCH of the topics over there, but figured it might be more useful to ask in a more general environment...

The system always boots from UEFI, and boot times HAVE NEVER been anywhere NEAR 30-36 seconds, but I did have them down to around 45 or so for a long time. Then this 80-90 second hang started.

I think I asked in here or somewhere a long time ago about any kind of log that can be generated, starting when it gets to the point where you hit DEL to enter the BIOS, while booting to see where the computer is spending all it's time during the boot. I don't think there was any such thing...

I don't know what a BIS is. The BIOS is current as of the last one they provided a while ago.

I've spent very little time in the AI Tweak area, using the basic tuning to get a mild overclock.

I can look and see what setting the DRAM timings are set to.

Beyond that, <slaps forehead and says "Doh">, I just realized I DIDN'T unplug peripherals... I've got a couple printers and a couple other things connected to USB ports... I have NO idea if these are part of the "super IO initialization" but I may as well unplug them boot and see if it matters.

Beyond that, I'll just have to hit reset once I get the "splash screen"? or whatever the thing is where you hit "DEL"...

I THINK it's fixed...

This morning I pulled EVERYTHING off the backplane of the system - except the network. Booted it, no delay. Plugged in the printers, fine. Plugged in the 4 additional USB3 extensions I have (I plug in a LOT of crap and there aren't enough USB3 ports on the front). Fine. Plugged in the cable that runs from the system to the monitor to provide USB for things plugged into the USB ports on the monitor....... DELAY.

Unplugged, fine. Plugged, DELAY. I removed everything plugged into the monitor (I hadn't thought about the couple USB devices plugged into the monitor, but its just the webcam, tried it - DELAY.

Moved the cable to a different, previously unused USB3 port - NO DELAY. Plugged back in the stuff on the monitor, and still no delay.

Once I got to this point I remembered that a while back I booted the system one day and it didn't see the mouse or keyboard. So, I pulled the dongle off the monitor and stuck it in a front panel port and have been working that way... Now I'm wondering if the reason the system couldn't find the devices was because of the cable.

In any case, AT THE MOMENT, there's no delay while booting, and I've got the fast boot and cold fast boot turned on in the BIOS - I didn't turn off train memory - there's a note in the bios when you hover on that about possible memory instability of you don't let it test, so I left it on...

Thanks for the responses. You guys got me pointed in the right direction. Now if I can just get this *&^%$#@ Outlook 2019 fixed!